RESUMEN

Fold-switching enables metamorphic proteins to reversibly interconvert between two highly dissimilar native states to regulate their protein functions. While about 100 proteins have been identified to undergo fold-switching, unveiling the key residues behind this mechanism for each protein remains challenging. Reasoning that fold-switching in proteins is driven by dynamic changes in local energetic frustration, we combined fold-switching simulations generated using simplified structure-based models with frustration analysis to identify key residues involved in this process based on the change in the density of minimally frustrated contacts during refolding. Using this approach to analyze the fold-switch of the bacterial transcription factor RfaH, we identified 20 residues that significantly change their frustration during its fold-switch, some of which have been experimentally and computationally reported in previous works. Our approach, which we developed as an additional module for the FrustratometeR package, highlights the role of local frustration dynamics in protein fold-switching and offers a robust tool to enhance our understanding of other proteins with significant conformational shifts.

Asunto(s)

Proteínas de Escherichia coli , Pliegue de Proteína , Proteínas de Escherichia coli/química , Proteínas de Escherichia coli/metabolismo , Transactivadores/química , Transactivadores/metabolismo , Transactivadores/genética , Simulación de Dinámica Molecular , Factores de Elongación de Péptidos/química , Factores de Elongación de Péptidos/metabolismo , Modelos Moleculares , Conformación Proteica , Termodinámica

RESUMEN

Escherichia coli is a frequent pathogen isolated from bloodstream infections. This study aimed to characterize the genetic features of EC092, an E. coli strain isolated from bacteremia that harbors enteroaggregative E. coli (EAEC) genetic markers, indicating its hybrid pathogenic potential. Whole-genome sequencing showed that EC092 belongs to phylogroup B1, ST278, and serotype O165:H4. Genes encoding virulence factors such as fimbriae, toxins, iron-uptake systems, autotransporter proteins (Pet, Pic, Sat, and SepA), and secretion systems were detected, as well as EAEC virulence genes (aggR, aatA, aaiC, and aap). EC092 was found to be closely related to the other EAEC prototype strains and highly similar in terms of virulence to three EAEC strains isolated from diarrhea. The genomic neighborhood of pet, pic, sat, sepA, and the EAEC virulence genes of EC092 and its three genetically related fecal EAEC strains showed an identical genomic organization and nucleotide sequences. Also, EC092 produced and secreted Pet, Pic, Sat, and SepA in the culture supernatant and resisted the bactericidal activity of normal human serum. Our results demonstrate that the strain EC092, isolated from bacteremia, is a hybrid pathogenic extraintestinal E. coli (ExPEC)/EAEC with virulence features that could mediate both extraintestinal and intestinal infections.

Asunto(s)

Bacteriemia , Infecciones por Escherichia coli , Escherichia coli , Genoma Bacteriano , Factores de Virulencia , Humanos , Bacteriemia/microbiología , Escherichia coli/genética , Escherichia coli/patogenicidad , Factores de Virulencia/genética , Infecciones por Escherichia coli/microbiología , Secuenciación Completa del Genoma , Virulencia/genética , Proteínas de Escherichia coli/genética , Proteínas de Escherichia coli/metabolismo , Filogenia , Genómica/métodos

RESUMEN

Atypical enteropathogenic Escherichia coli (aEPEC) is a significant cause of diarrhea in low- and middle-income countries. Certain aEPEC strains, including the Brazilian representative strain of serotype O51:H40 called aEPEC 1711-4, can use flagella to attach to, invade, and persist in T84 and Caco-2 intestinal cells. It can also translocate from the gut to extraintestinal sites in a rat model. Although various aspects of the virulence of this strain were studied and the requirement of a type III secretion system for the efficiency of the invasion process was demonstrated, the expression of the locus of enterocyte effacement (LEE) genes during the invasion and intracellular persistence remains unclear. To address this question, the expression of flagella and the different LEE operons was evaluated during kinetic experiments of the interaction of aEPEC 1711-4 with enterocytes in vitro. The genome of the strain was also sequenced. The results showed that flagella expression remained unchanged, but the expression of eae and escJ increased during the early interaction and invasion of aEPEC 1711-4 into Caco-2 cells, and there was no change 24 h post-infection during the persistence period. The number of actin accumulation foci formed on HeLa cells also increased during the 6-h analysis. No known gene related to the invasion process was identified in the genome of aEPEC 1711-4, which was shown to belong to the global EPEC lineage 10. These findings suggest that the LEE components and the intimate adherence promoted by intimin are necessary for the invasion and persistence of aEPEC 1711-4, but the detailed mechanism needs further study.IMPORTANCEAtypical enteropathogenic Escherichia coli (aEPEC) is a major cause of diarrhea, especially in low- and middle-income countries, like Brazil. However, due to the genome heterogeneity of each clonal group, it is difficult to comprehend the pathogenicity of this strain fully. Among aEPEC strains, 1711-4 can invade eukaryotic cells in vitro, cross the gut barrier, and reach extraintestinal sites in animal models. By studying how different known aEPEC virulence factors are expressed during the invasion process, we can gain insight into the commonalities of this phenotype among other aEPEC strains. This will help in developing preventive measures to control infections caused by invasive strains. No known virulence-encoding genes linked to the invasion process were found. Nevertheless, additional studies are still necessary to evaluate the role of other factors in this phenotype.

Asunto(s)

Enterocitos , Escherichia coli Enteropatógena , Infecciones por Escherichia coli , Proteínas de Escherichia coli , Flagelos , Serogrupo , Escherichia coli Enteropatógena/genética , Escherichia coli Enteropatógena/patogenicidad , Escherichia coli Enteropatógena/metabolismo , Humanos , Proteínas de Escherichia coli/genética , Proteínas de Escherichia coli/metabolismo , Enterocitos/microbiología , Células CACO-2 , Infecciones por Escherichia coli/microbiología , Flagelos/genética , Flagelos/metabolismo , Virulencia/genética , Fosfoproteínas/genética , Fosfoproteínas/metabolismo , Regulación Bacteriana de la Expresión Génica , Adhesión Bacteriana/genética , Animales , Brasil , Factores de Virulencia/genética , Factores de Virulencia/metabolismo , Operón/genética , Ratas

RESUMEN

The collective involvement of virulence markers of Escherichia coli as an emerging pathogen associated with periodontitis remains unexplained. This study aimed to implement an in vitro model of infection using a human epithelial cell line to determine the virulome expression related to the antibiotic and disinfectant resistance genotype and pulse field gel electrophoresis (PFGE) type in E. coli strains isolated from patients with periodontal diseases. We studied 100 strains of E. coli isolated from patients with gingivitis (n = 12), moderate periodontitis (n = 59), and chronic periodontitis (n = 29). The identification of E. coli and antibiotic and disinfectant resistance genes was performed through PCR. To promote the expression of virulence genes in the strains, an in vitro infection model was used in the human epithelial cell line A549. RNA was extracted using the QIAcube robotic equipment and reverse transcription to cDNA was performed using the QuantiTect reverse transcription kit (Qiagen). The determination of virulence gene expression was performed through real-time PCR. Overall, the most frequently expressed adhesion genes among the isolated strains of gingivitis, moderate periodontitis, and chronic periodontitis were fimH (48%), iha (37%), and papA (18%); those for toxins were usp (33%); those for iron acquisition were feoB (84%), fyuA (62%), irp-2 (61%), and iroN (35%); those for protectins were traT (50%), KpsMT (35%), and ompT (28%); and those for pathogenicity islands were malX (45%). The most common antibiotic and disinfectant resistance genes among gingivitis, moderate periodontitis, and chronic periodontitis strains were sul-2 (43%), blaSHV (47%), blaTEM (45%), tet(A) (41%), dfrA1 (32%), marR-marO (57%), and qacEA1 (79%). The findings revealed the existence of a wide distribution of virulome expression profiles related to the antibiotic and disinfectant resistance genotype and PFGE type in periodontal strains of E. coli. These findings may contribute toward improving the prevention and treatment measures for periodontal diseases associated with E. coli.

Asunto(s)

Antibacterianos , Desinfectantes , Farmacorresistencia Bacteriana , Infecciones por Escherichia coli , Escherichia coli , Factores de Virulencia , Humanos , Escherichia coli/genética , Escherichia coli/efectos de los fármacos , Escherichia coli/patogenicidad , Factores de Virulencia/genética , Antibacterianos/farmacología , Infecciones por Escherichia coli/microbiología , Farmacorresistencia Bacteriana/genética , Desinfectantes/farmacología , Periodontitis/microbiología , Virulencia/genética , Células A549 , Células Epiteliales/microbiología , Genotipo , Adulto , Femenino , Masculino , Persona de Mediana Edad , Proteínas de Escherichia coli/genética , Proteínas de Escherichia coli/metabolismo , Electroforesis en Gel de Campo Pulsado

RESUMEN

In Escherichia coli, the disaccharide trehalose can be metabolized as a carbon source or be accumulated as an osmoprotectant under osmotic stress. In hypertonic environments, E. coli accumulates trehalose in the cell by synthesis from glucose mediated by the cytosolic enzymes OtsA and OtsB. Trehalose in the periplasm can be hydrolyzed into glucose by the periplasmic trehalase TreA. We have previously shown that a treA mutant of extraintestinal E. coli strain BEN2908 displayed increased resistance to osmotic stress by 0.6 M urea, and reduced production of type 1 fimbriae, reduced invasion of avian fibroblasts, and decreased bladder colonization in a murine model of urinary tract infection. Since loss of TreA likely results in higher periplasmic trehalose concentrations, we wondered if deletion of otsA and otsB genes, which would lead to decreased internal trehalose concentrations, would reduce resistance to stress by 0.6 M urea and promote type 1 fimbriae production. The BEN2908ΔotsBA mutant was sensitive to osmotic stress by urea, but displayed an even more pronounced reduction in production of type 1 fimbriae, with the consequent reduction in adhesion/invasion of avian fibroblasts and reduced bladder colonization in the murine urinary tract. The BEN2908ΔtreAotsBA mutant also showed a reduction in production of type 1 fimbriae, but in contrast to the ΔotsBA mutant, resisted better than the wild type in the presence of urea. We hypothesize that, in BEN2908, resistance to stress by urea would depend on the levels of periplasmic trehalose, but type 1 fimbriae production would be influenced by the levels of cytosolic trehalose.

Asunto(s)

Fimbrias Bacterianas , Osmorregulación , Trehalosa , Vejiga Urinaria , Infecciones Urinarias , Animales , Trehalosa/metabolismo , Ratones , Vejiga Urinaria/microbiología , Fimbrias Bacterianas/metabolismo , Fimbrias Bacterianas/genética , Infecciones Urinarias/microbiología , Infecciones por Escherichia coli/microbiología , Proteínas de Escherichia coli/metabolismo , Proteínas de Escherichia coli/genética , Escherichia coli/metabolismo , Escherichia coli/genética , Modelos Animales de Enfermedad , Femenino , Presión Osmótica , Escherichia coli Patógena Extraintestinal/metabolismo , Escherichia coli Patógena Extraintestinal/genética , Urea/metabolismo , Trehalasa/metabolismo , Trehalasa/genética , Eliminación de Gen , Glucosa/metabolismo

RESUMEN

Background: Urinary tract infections (UTIs) are very common worldwide. According to their symptomatology, these infections are classified as pyelonephritis, cystitis, or asymptomatic bacteriuria (AB). Approximately 75-95% of UTIs are caused by uropathogenic Escherichia coli (UPEC), which is an extraintestinal bacterium that possesses virulence factors for bacterial adherence and invasion in the urinary tract. In addition, UPEC possesses type 6 secretion systems (T6SS) as virulence mechanisms that can participate in bacterial competition and in bacterial pathogenicity. UPEC UMN026 carries three genes, namely, ECUMN_0231, ECUMN_0232, and ECUMN_0233, which encode three uncharacterized proteins related to the T6SS that are conserved in strains from phylogroups B2 and D and have been proposed as biomarkers of UTIs. Aim: To analyze the frequency of the ECUMN_0231, ECUMN_0232, ECUMN_0233, and vgrG genes in UTI isolates, as well as their expression in Luria Bertani (LB) medium and urine; to determine whether these genes are related to UTI symptoms or bacterial competence and to identify functional domains on the putative proteins. Methods: The frequency of the ECUMN and vgrG genes in 99 clinical isolates from UPEC was determined by endpoint PCR. The relationship between gene presence and UTI symptomatology was determined using the chi2 test, with p < 0.05 considered to indicate statistical significance. The expression of the three ECUMN genes and vgrG was analyzed by RT-PCR. The antibacterial activity of strain UMN026 was determined by bacterial competence assays. The identification of functional domains and the docking were performed using bioinformatic tools. Results: The ECUMN genes are conserved in 33.3% of clinical isolates from patients with symptomatic and asymptomatic UTIs and have no relationship with UTI symptomatology. Of the ECUMN+ isolates, only five (15.15%, 5/33) had the three ECUMN and vgrG genes. These genes were expressed in LB broth and urine in UPEC UMN026 but not in all the clinical isolates. Strain UMN026 had antibacterial activity against UPEC clinical isolate 4014 (ECUMN-) and E. faecalis but not against isolate 4012 (ECUMN+). Bioinformatics analysis suggested that the ECUMN genes encode a chaperone/effector/immunity system. Conclusions: The ECUMN genes are conserved in clinical isolates from symptomatic and asymptomatic patients and are not related to UTI symptoms. However, these genes encode a putative chaperone/effector/immunity system that seems to be involved in the antibacterial activity of strain UMN026.

Asunto(s)

Infecciones por Escherichia coli , Proteínas de Escherichia coli , Chaperonas Moleculares , Infecciones Urinarias , Escherichia coli Uropatógena , Escherichia coli Uropatógena/inmunología , Escherichia coli Uropatógena/genética , Escherichia coli Uropatógena/patogenicidad , Humanos , Infecciones Urinarias/microbiología , Infecciones Urinarias/inmunología , Chaperonas Moleculares/genética , Chaperonas Moleculares/metabolismo , Infecciones por Escherichia coli/inmunología , Infecciones por Escherichia coli/microbiología , Proteínas de Escherichia coli/genética , Proteínas de Escherichia coli/inmunología , Proteínas de Escherichia coli/metabolismo , Femenino , Factores de Virulencia/genética , Factores de Virulencia/inmunología , Masculino , Persona de Mediana Edad , Adulto

RESUMEN

We investigated bile salts' ability to induce phenotypic changes in biofilm production and protein expression of pathogenic Escherichia coli strains. For this purpose, 82 pathogenic E. coli strains isolated from humans (n = 70), and animals (n = 12), were examined for their ability to form biofilms in the presence or absence of bile salts. We also identified bacterial proteins expressed in response to bile salts using sodium dodecyl-sulfate polyacrylamide gel electrophoresis (SDS-electrophoresis) and liquid chromatography-mass spectrometry (LC-MS/MS). Lastly, we evaluated the ability of these strains to adhere to Caco-2 epithelial cells in the presence of bile salts. Regarding biofilm formation, two strains isolated from an outbreak in Republic of Georgia in 2009 were the only ones that showed a high and moderate capacity to form biofilm in the presence of bile salts. Further, we observed that those isolates, when in the presence of bile salts, expressed different proteins identified as outer membrane proteins (i.e. OmpC), and resistance to adverse growth conditions (i.e. F0F1, HN-S, and L7/L12). We also found that these isolates exhibited high adhesion to epithelial cells in the presence of bile salts. Together, these results contribute to the phenotypic characterization of E. coli O104: H4 strains.

Asunto(s)

Infecciones por Escherichia coli , Escherichia coli O104 , Proteínas de Escherichia coli , Escherichia coli Shiga-Toxigénica , Animales , Humanos , Escherichia coli/metabolismo , Virulencia , Células CACO-2 , Cromatografía Liquida , Espectrometría de Masas en Tándem , Biopelículas , Infecciones por Escherichia coli/microbiología , Proteínas de Escherichia coli/genética , Proteínas de Escherichia coli/metabolismo

RESUMEN

This study aimed to determine the prevalence of cyclomodulins (cdt, cnf, pks and cif) in Escherichia coli (E. coli) isolated from clinical and environmental samples, the presence of supplementary virulence genes (SVG), antibiotic resistance, and in vitro cytotoxicity. 413 E. coli were isolated from clinical (stool from obese subjects, normal weight subjects, children with diarrhea, and children without diarrhea; and urine from pregnant and non-pregnant women with urinary tract infections) and environmental (water and different foods) samples. PCR was performed to identify E. coli pathotypes, the four cyclomodulins, and 18 SVG; virulence score, cytotoxic assay, and antibiotic resistance assay were performed. Fifteen percent of E. coli were positive for cyclomodulins and were found in all isolation sources; however, in children with diarrhea, they were more frequent. The most frequent cyclomodulin was cdt. More DEC strains harbor cyclomodulins than non-DEC, and cyclomodulins were most frequent among aEPEC pathotype. SVG ehaC was associated with cyclomodulin-positive strains. Cyclomodulin-positive E. coli had a higher virulence score but no significant cytotoxic activity. They were slightly more resistant to antibiotics. In conclusion, cyclomodulins-positive E. coli was widely distributed in humans, food, and the environment, and they were associated with SVG ehaC, suggesting that these genes may play a role in the pathogenesis of the cyclomodulins. However, more research is needed.

Asunto(s)

Diarrea , Infecciones por Escherichia coli , Proteínas de Escherichia coli , Escherichia coli , Factores de Virulencia , Humanos , Escherichia coli/genética , Escherichia coli/patogenicidad , Escherichia coli/efectos de los fármacos , Escherichia coli/aislamiento & purificación , Factores de Virulencia/genética , Infecciones por Escherichia coli/microbiología , Femenino , Proteínas de Escherichia coli/genética , Proteínas de Escherichia coli/metabolismo , Diarrea/microbiología , Virulencia/genética , Niño , Antibacterianos/farmacología , Heces/microbiología , Embarazo , Infecciones Urinarias/microbiología , Microbiología Ambiental , Farmacorresistencia Bacteriana/genética , Masculino , Adulto

RESUMEN

The identification of genes associated with resistance has the potential to facilitate the development of novel diagnostic tests and treatment methods. The objective of this study was to examine the antibiotic resistance and Fosfomycin resistance genes in uropathogenic Escherichia coli (UPEC) in patients in Baghdad, Iraq. After analyzing 250 urine samples using various identification methods, including the examination of morphological characteristics, biochemical tests, and genetic detection, it was determined that E. coli was the most common bacteria present, accounting for 63.6% of the samples. Antibiotic susceptibility testing showed a significant prevalence of resistance to various antibiotics, with 99.3% of E. coli isolates exhibiting multiple drug resistance (MDR). Fosfomycin showed antibacterial properties against UPEC. The minimum inhibitory concentration (MIC) ranged from 512 to 1024 µg/mL, while the minimum bactericidal concentration (MBC) was 2048 µg/mL. In the time-kill assay, fosfomycin was effective against fosfomycin-resistant isolates within 8-12 h. The genetic determinants associated with fosfomycin resistance were examined through the utilization of polymerase chain reaction (PCR). The findings indicated that the genes murA, glpT, and cyaA were detected in all the isolates when genomic DNA was used as a template. However, all the tests yielded negative results when plasmid was used as a template. The genes fosA3 and fosA4 were detected in 8.6% and 5% of the isolates when genomic DNA was used as a template. When plasmid was used as a template, the genes fosA3 and fosA4 were found in 5.7% and 2.9% of the isolates, respectively. In conclusion, there is an increasing problem with antibiotic resistance in UPEC, with elevated rates of resistance to several antibiotics. The study also offers novel insights into the genetic foundation of fosfomycin resistance in UPEC.

Asunto(s)

Antibacterianos , Infecciones por Escherichia coli , Fosfomicina , Pruebas de Sensibilidad Microbiana , Infecciones Urinarias , Escherichia coli Uropatógena , Fosfomicina/farmacología , Escherichia coli Uropatógena/genética , Escherichia coli Uropatógena/efectos de los fármacos , Escherichia coli Uropatógena/aislamiento & purificación , Humanos , Antibacterianos/farmacología , Infecciones por Escherichia coli/microbiología , Infecciones Urinarias/microbiología , Farmacorresistencia Bacteriana/genética , Irak , Femenino , Masculino , Adulto , Proteínas de Escherichia coli/genética , Proteínas de Escherichia coli/metabolismo , Adulto Joven , Persona de Mediana Edad , Adolescente , Farmacorresistencia Bacteriana Múltiple/genética

RESUMEN

Plasmid-encoded toxin (Pet) is an autotransporter protein of the serine protease autotransporters of Enterobacteriaceae (SPATE) family, important in the pathogenicity of Escherichia coli. The pet gene was initially found in the enteroaggregative E. coli (EAEC) virulence plasmid, pAA2. Although this virulence factor was initially described in EAEC, an intestinal E. coli pathotype, pet may also be present in other pathotypes, including extraintestinal pathogenic strains (ExPEC). The complement system is an important defense mechanism of the immune system that can be activated by invading pathogens. Proteases produced by pathogenic bacteria, such as SPATEs, have proteolytic activity and can cleave components of the complement system, promoting bacterial resistance to human serum. Considering these factors, the proteolytic activity of Pet and its role in evading the complement system were investigated. Proteolytic assays were performed by incubating purified components of the complement system with Pet and Pet S260I (a catalytic site mutant) proteins. Pet, but not Pet S260I, could cleave C3, C5 and C9 components, and also inhibited the natural formation of C9 polymers. Furthermore, a dose-dependent inhibition of ZnCl2-induced C9 polymerization in vitro was observed. E. coli DH5α survived incubation with human serum pre-treated with Pet. Therefore, Pet can potentially interfere with the alternative and the terminal pathways of the complement system. In addition, by cleaving C9, Pet may inhibit membrane attack complex (MAC) formation on the bacterial outer membrane. Thus, our data are suggestive of a role of Pet in resistance of E. coli to human serum.

Asunto(s)

Toxinas Bacterianas , Infecciones por Escherichia coli , Proteínas de Escherichia coli , Humanos , Escherichia coli/metabolismo , Toxinas Bacterianas/metabolismo , Proteínas de Escherichia coli/genética , Proteínas de Escherichia coli/metabolismo , Proteínas del Sistema Complemento/metabolismo , Serina Proteasas/metabolismo , Infecciones por Escherichia coli/microbiología , Plásmidos/genética

RESUMEN

Shiga toxin-producing Escherichia coli (STEC) are recognized as being responsible for many cases of foodborne diseases worldwide. Cattle are the main reservoir of STEC, shedding the microorganisms in their feces. The serogroup STEC O91 has been associated with hemorrhagic colitis and hemolytic uremic syndrome. Locus of Adhesion and Autoaggregation (LAA) and its hes gene are related to the pathogenicity of STEC and the ability to form biofilms. Considering the frequent isolation of STEC O91, the biofilm-forming ability, and the possible role of hes in the pathogenicity of STEC, we propose to evaluate the ability of STEC to form biofilms and to evaluate the expression of hes before and after of biofilm formation. All strains were classified as strong biofilm-forming. The hes expression showed variability between strains before and after biofilm formation, and this may be due to other genes carried by each strain. This study is the first to report the relationship between biofilm formation, and hes expression and proposes that the analysis and diagnosis of LAA, especially hes as STEC O91 virulence factors, could elucidate these unknown mechanisms. Considering that there is no specific treatment for HUS, only supportive care, it is necessary to know the survival and virulence mechanisms of STEC O91.

Asunto(s)

Biopelículas , Proteínas de Escherichia coli , Escherichia coli Shiga-Toxigénica , Biopelículas/crecimiento & desarrollo , Escherichia coli Shiga-Toxigénica/genética , Escherichia coli Shiga-Toxigénica/fisiología , Escherichia coli Shiga-Toxigénica/patogenicidad , Proteínas de Escherichia coli/genética , Proteínas de Escherichia coli/metabolismo , Regulación Bacteriana de la Expresión Génica , Animales , Bovinos , Infecciones por Escherichia coli/veterinaria , Infecciones por Escherichia coli/microbiología , Transcripción Genética

RESUMEN

Alpha hemolysin (HlyA) is a hemolytic and cytotoxic protein secreted by uropathogenic strains of E. coli. The role of glycophorins (GPs) as putative receptors for HlyA binding to red blood cells (RBCs) has been debated. Experiments using anti-GPA/GPB antibodies and a GPA-specific epitope nanobody to block HlyA-GP binding on hRBCs, showed no effect on hemolytic activity. Similarly, the hemolysis induced by HlyA remained unaffected when hRBCs from a GPAnull/GPBnull variant were used. Surface Plasmon Resonance experiments revealed similar values of the dissociation constant between GPA and either HlyA, ProHlyA (inactive protoxin), HlyAΔ914-936 (mutant of HlyA lacking the binding domain to GPA) or human serum albumin, indicating that the binding between the proteins and GPA is not specific. Although far Western blot followed by mass spectroscopy analyses suggested that HlyA interacts with Band 3 and spectrins, hemolytic experiments on spectrin-depleted hRBCs and spherocytes, indicated these proteins do not mediate the hemolytic process. Our results unequivocally demonstrate that neither glycophorins, nor Band 3 and spectrins mediate the cytotoxic activity of HlyA on hRBCs, thereby challenging the HlyA-receptor hypothesis. This finding holds significant relevance for the design of anti-toxin therapeutic strategies, particularly in light of the growing antibiotic resistance exhibited by bacteria.

Asunto(s)

Proteínas de Escherichia coli , Toxinas Biológicas , Humanos , Escherichia coli/metabolismo , Proteínas de Escherichia coli/metabolismo , Proteínas Hemolisinas/farmacología , Proteínas Hemolisinas/química , Proteínas Hemolisinas/metabolismo , Proteínas de la Membrana/metabolismo , Glicoforinas/metabolismo , Glicoforinas/farmacología , Hemólisis , Eritrocitos/metabolismo , Toxinas Biológicas/metabolismo

RESUMEN

The spread of ESBL-producing Escherichia coli has constantly increased in both clinical and community infections. Actually, the main ESBL reported is the CTX-M family, which is widely disseminated between the Enterobacteriaceae family. The epidemiology of the CTX-M family shows the CTX-M-15 variant dominating worldwide, followed by CTX-M-14 and CTX-M-27. The specific ESBL-producing E. coli clones included mainly the sequence types ST131, ST405, and ST648. In this report, we present the molecular characterization of ESBL-producing E. coli clinical isolates from eight hospitals in Mexico. From a collection of 66 isolates, 39 (59%) were identified as blaCTX-M-14 and blaCTX-M-27 belonging to the group CTX-M-9. We identified 25 (38%) isolates, producing blaCTX-M-28 belonging to the group CTX-M-1. blaCTX-M-2 and blaTEM-55 were identified in one isolate, respectively. Fourteen isolates (21%) were positive for blaCTX-M-14 (13%) and blaCTX-M-28 (7.3%) that were selected for further analyses; the antimicrobial susceptibility showed resistance to ampicillin (> 256 µg/mL), cefotaxime (> 256 µg/mL), cefepime (> 64 µg/mL), and ceftazidime (16 µg/mL). The ResFinder analysis showed the presence of the antimicrobial resistance genes aacA4, aadA5, aac(3)lla, sul1, dfrA17, tet(A), cmlA1, and blaTEM-1B. PlasmidFinder analysis identified in all the isolates the replicons IncFIB, which were confirmed by PCR replicon typing. The MLST analysis identified isolates belonging to ST131, ST167, ST405, and ST648. The ISEcp1B genetic element was found at 250 pb upstream of blaCTX-M-14 and flanked by the IS903 genetic element at 35 pb downstream. The IS1380-like element ISEc9 family transposase was identified at 250 pb upstream of blaCTX-M-14 and flanked downstream by the IS5/IS1182 at 80 pb. Our study highlights the significant prevalence of CTX-M-14 and CTX-M-28 enzymes as the second-most common ESBL-producing E. coli among isolates in Mexican hospitals. The identification of specific sequence types in different regions provides valuable insights into the correlation between ESBL and E. coli strains. This contribution to understanding their epidemiology and potential transmission routes is crucial for developing effective strategies to mitigate the spread of ESBL-producing E. coli in healthcare settings.

Asunto(s)

Antiinfecciosos , Infecciones por Escherichia coli , Humanos , Antibacterianos/farmacología , beta-Lactamasas/genética , Escherichia coli , Infecciones por Escherichia coli/epidemiología , Infecciones por Escherichia coli/microbiología , México , Tipificación de Secuencias Multilocus , Proteínas de Escherichia coli/genética , Proteínas de Escherichia coli/metabolismo

RESUMEN

In this study, molecular dynamics (MD) and docking simulations were carried out on the crystal structure of Neisseria Gonorrhoeae RsmE aiming at free energy of binding estimation (ΔGbinding) of the methyl transfer substrate S-adenosylmethionine (SAM), as well as its homocysteine precursor S-adenosylhomocysteine (SAH). The mechanistic insight gained was generalized in view of existing homology to two other crystal structures of RsmE from Escherichia coli and Aquifex aeolicus. As a proof of concept, the crystal poses of SAM and SAH were reproduced reflecting a more general pattern of molecular interaction for bacterial RsmEs. Our results suggest that a distinct set of conserved residues on loop segments between ß12, α6, and Met169 are interacting with SAM and SAH across these bacterial methyltransferases. Comparing molecular movements over time (MD trajectories) between Neisseria gonorrhoeae RsmE alone or in the presence of SAH revealed a hitherto unknown gatekeeper mechanism by two isoleucine residues, Ile171 and Ile219. The proposed gating allows switching from an open to a closed state, mimicking a double latch lock. Additionally, two key residues, Arg221 and Thr222, were identified to assist the exit mechanism of SAH, which could not be observed in the crystal structures. To the best of our knowledge, this study describes for the first time a general catalytic mechanism of bacterial RsmE on theoretical ground.

Asunto(s)

Proteínas de Escherichia coli , Metiltransferasas , Metiltransferasas/metabolismo , ARN Ribosómico 16S/genética , Simulación de Dinámica Molecular , Metilación , Escherichia coli/genética , Escherichia coli/metabolismo , S-Adenosilmetionina/metabolismo , Proteínas de Escherichia coli/metabolismo

RESUMEN

Escherichia coli cells rapidly respond to changes in the environment. Such response must be anticipated upon development of fermentation strategy for commercial purposes. The response may signal changes in cell physiology, which is critical for the cell growth and the level of the target protein production. One of the responses is the elevated expression of membrane proteins to tightly control the trafficking of molecules into and out from the cells. Normally, the expression level of the membrane protein is basal as the fermentation is carried out in physiological conditions. Here, we reported an elevated expression of the outer membrane protein A (OmpA) during a series of fermentation conduct, starting from the shake flask, 1-L to finally 10-L fermentor. The incidence led to a lower expression of the target protein and thereby resulting in lower process efficiency. OmpA expression was concomitant to the bacterial growth and already observed in the early exponential phase. Despite the drawback, this phenomenon actually inspires the observation of OmpA expression as one of the indicators for the E. coli cells response to the fermentation conditions. This auxiliary check would prevent the higher OmpA expression that led to the low expression of the target protein.

Asunto(s)

Proteínas de Escherichia coli , Escherichia coli , Escherichia coli/metabolismo , Proteínas de la Membrana Bacteriana Externa/genética , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Proteínas de Escherichia coli/genética , Proteínas de Escherichia coli/metabolismo

RESUMEN

Twenty-two atypical enteroaggregative Escherichia coli isolates from a previous epidemiological study harboring EAEC virulence genes were examined for their adhesion properties. Nine strains showed a typical aggregative adherence (AA) pattern, while 13 strains showed variant AA, such as AA with lined up cells characteristic of the chain-like adhesion (CLA) and AA mainly to HeLa cells characteristic of the diffuse adherence (DA). The aggregative forming pilus (AFP) genes afpA2 and afpR were detected only in strain Q015B, which exhibited an AA/DA pattern. Using Tn5-based transposon mutagenesis on Q015B strain, we identified a 5517-bp open reading frame (ORF) encoding a predicted 1838-amino-acid polypeptide that is genetically related to a putative filamentous hemagglutinin identified in E. coli strain 7-233-03_S3_C2. Therefore, the ORF was named orfHA. The regions flanking orfHA were sequenced and two ORFs were found; upstream, an ORF that encodes a 603-amino-acid polypeptide with 99% identity to hemolysin secretion/activation proteins of the ShlB/FhaC/HecB family, and downstream, another ORF, which encodes a 632-amino-acid polypeptide with 72% identity to the glycosyltransferase EtpC. An orfHA mutant (Q015BΔorfHA) was constructed from strain Q015B. Q015BΔorfHA strain did not adhere to HeLa cells, whereas Q015BΔ orfHA transformed with a pACYC184 plasmid carrying orfHA restored the AA/DA phenotype of strain Q015B. Furthermore, the Q015ΔorfHA mutant had a marked effect on the ability of strain Q015B to kill the larvae of Galleria mellonella. Our results suggest that the AA/DA pattern of strain Q015B is mediated by a hemagglutinin-associated protein which also contributes to its virulence in the G. mellonella model.

Asunto(s)

Infecciones por Escherichia coli , Proteínas de Escherichia coli , Humanos , Escherichia coli/metabolismo , Hemaglutininas/metabolismo , Células HeLa , Proteínas de Escherichia coli/genética , Proteínas de Escherichia coli/metabolismo , Virulencia/genética , Adhesión Celular , Adhesión Bacteriana/genética , Infecciones por Escherichia coli/genética , Mutagénesis

RESUMEN

In several Gram-negative bacteria, the general stress response is mediated by the alternative sigma factor RpoS, a subunit of RNA polymerase that confers promoter specificity. In Escherichia coli, regulation of protein levels of RpoS involves the adaptor protein RssB, which binds RpoS for presenting it to the ClpXP protease for its degradation. However, in species from the Pseudomonadaceae family, RpoS is also degraded by ClpXP, but an adaptor has not been experimentally demonstrated. Here, we investigated the role of an E. coli RssB-like protein in two representative Pseudomonadaceae species such as Azotobacter vinelandii and Pseudomonas aeruginosa. In these bacteria, inactivation of the rssB gene increased the levels and stability of RpoS during exponential growth. Downstream of rssB lies a gene that encodes a protein annotated as an anti-sigma factor antagonist (rssC). However, inactivation of rssC in both A. vinelandii and P. aeruginosa also increased the RpoS protein levels, suggesting that RssB and RssC work together to control RpoS degradation. Furthermore, we identified an in vivo interaction between RssB and RpoS only in the presence of RssC using a bacterial three-hybrid system. We propose that both RssB and RssC are necessary for the ClpXP-dependent RpoS degradation during exponential growth in two species of the Pseudomonadaceae family.

Asunto(s)

Azotobacter vinelandii , Proteínas de Escherichia coli , Factor sigma/genética , Factor sigma/metabolismo , Factores de Transcripción/metabolismo , Escherichia coli/metabolismo , Proteínas de Unión al ADN/metabolismo , Pseudomonas aeruginosa/genética , Pseudomonas aeruginosa/metabolismo , Proteínas de Escherichia coli/metabolismo , Azotobacter vinelandii/genética , Azotobacter vinelandii/metabolismo , Proteínas Bacterianas/genética , Proteínas Bacterianas/metabolismo , Regulación Bacteriana de la Expresión Génica

RESUMEN

Enterotoxigenic Escherichia coli (ETEC) strains produce at least one of two types of enterotoxins: the heat-labile (LT) and heat-stable (ST) toxins, which are responsible for the watery secretory diarrhoea that is a hallmark of the human ETEC infection. One regulatory system that controls the transcription of virulence genes in pathogenic bacteria is the CpxRA two-component system (TCS). We reported that the eltAB bicistronic operon, which encodes for the A and B subunits of LT, was repressed for the CpxRA TCS by direct binding of CpxR-P from -12 to +6 bp with respect to the transcription start site of eltAB. Moreover, the Cpx-response activation down-regulated the transcription of eltAB genes, and this negative effect was CpxRA-dependent. Our data show that CpxRA TCS is a negative regulator of the LT, one of the main virulence determinants of ETEC.

Asunto(s)

Toxinas Bacterianas , Escherichia coli Enterotoxigénica , Infecciones por Escherichia coli , Proteínas de Escherichia coli , Humanos , Escherichia coli Enterotoxigénica/genética , Escherichia coli Enterotoxigénica/metabolismo , Toxinas Bacterianas/genética , Toxinas Bacterianas/metabolismo , Calor , Proteínas de Escherichia coli/genética , Proteínas de Escherichia coli/metabolismo , Enterotoxinas/genética , Enterotoxinas/metabolismo , Infecciones por Escherichia coli/microbiología , Diarrea/microbiología , Expresión Génica

RESUMEN

The function of chaperones is to correct or degrade misfolded proteins inside the cell. Classic molecular chaperones such as GroEL and DnaK have not been found in the periplasm of Yersinia pseudotuberculosis. Some periplasmic substrate-binding proteins could be bifunctional, such as OppA. Using bioinformatic tools, we try to elucidate the nature of the interactions between OppA and ligands from four proteins with different oligomeric states. Using the crystal structure of the proteins Mal12 alpha-glucosidase from Saccharomyces cerevisiae S288C, LDH rabbit muscle lactate dehydrogenase, EcoRI endonuclease from Escherichia coli and THG Geotrichum candidum lipase, a hundred models were obtained in total, including five different ligands from each enzyme with five conformations of each ligand. The best values for Mal12 stem from ligands 4 and 5, with conformation 5 for both; for LDH, ligands 1 and 4, with conformations 2 and 4, respectively; for EcoRI, ligands 3 and 5, with conformation 1 for both; and for THG, ligands 2 and 3, with conformation 1 for both. The interactions were analyzed with LigProt, and the length of the hydrogen bridges has an average of 2.8 to 3.0 Å. The interaction within the OppA pocket is energetically favored due to the formation of hydrogen bonds both of OppA and of the selected enzymes. The Asp 419 residue is important in these junctions.

Asunto(s)

Proteínas Bacterianas , Chaperonas Moleculares , Proteínas de Unión Periplasmáticas , Yersinia pseudotuberculosis , Animales , Conejos , Proteínas Bacterianas/metabolismo , Sitios de Unión , Proteínas Portadoras/metabolismo , Escherichia coli/metabolismo , Proteínas de Escherichia coli/metabolismo , Ligandos , Chaperonas Moleculares/metabolismo , Proteínas de Unión Periplasmáticas/metabolismo , Unión Proteica , Yersinia pseudotuberculosis/metabolismo

RESUMEN

In enteropathogenic Escherichia coli (EPEC), the production of flagella and the type III secretion system (T3SS) is activated in the presence of host cultured epithelial cells. The goal of this study was to investigate the relationship between expression of flagella and the T3SS. Mutants deficient in assembling T3SS basal and translocon components (ΔespA, ΔespB, ΔespD, ΔescC, ΔescN, and ΔescV), and in secreting effector molecules (ΔsepD and ΔsepL) were tested for flagella production under several growth conditions. The ΔespA mutant did not produce flagella in any condition tested, although fliC was transcribed. The remaining mutants produced different levels of flagella upon growth in LB or in the presence of cells but were significantly diminished in flagella production after growth in Dulbecco's minimal essential medium. We also investigated the role of virulence and global regulator genes in expression of flagella. The ΔqseB and ΔqseC mutants produced abundant flagella only when growing in LB and in the presence of HeLa cells, indicating that QseB and QseC act as negative regulators of fliC transcription. The ΔgrlR, ΔperA, Δler, Δhns, and Δfis mutants produced low levels of flagella, suggesting these regulators are activators of fliC expression. These data suggest that the presence of an intact T3SS is required for assembly of flagella highlighting the existence in EPEC of a cross-talk between these two virulence-associated T3SSs.

Asunto(s)

Escherichia coli Enteropatógena , Proteínas de Escherichia coli , Humanos , Escherichia coli Enteropatógena/genética , Escherichia coli Enteropatógena/metabolismo , Sistemas de Secreción Tipo III/genética , Sistemas de Secreción Tipo III/metabolismo , Proteínas de Escherichia coli/genética , Proteínas de Escherichia coli/metabolismo , Células HeLa , Regulación Bacteriana de la Expresión Génica , Flagelos/genética , Flagelos/metabolismo