RESUMO
AIMS: Although Shiga toxins (Stx) are well-established virulence traits of O113:H21 Shigatoxigenic Escherichia coli (STEC) strains, a shortage in the knowledge of other virulence properties that may contribute to pathogenesis may exist in this serotype. This study investigated biofilm, invasiveness and colicinogeny capabilities in O113:H21 STEC isolated in Brazil, mostly from animal reservoirs. A search for genes that were reported to participate in the process of biofilm formation was also performed. METHODS AND RESULTS: The 34 O113:H21 STEC isolates analysed were assayed for biofilm production in polystyrene microplates. Genes for biofilm were investigated by PCR. Invasion of cell lineages was assessed in gentamicin protection assays and colicinogeny was investigated by phenotypic tests. Fifty per cent of the strains were biofilm formers, and 35% exhibited an invasive behaviour. The pattern of distribution of biofilm-related genes did not correlate with biofilm phenotypes observed, and a high percentage of the investigated strains were able to secrete colicins. CONCLUSION: Ability to form biofilm, invasiveness and colicinogeny is demonstrated for the first time in a collection of O113:H21 STEC. SIGNIFICANCE AND IMPACT OF THE STUDY: The ability to express three additional phenotypes besides Stx production may be a factor influencing the pathogenicity and persistence potential of O113:H21 STEC.
Assuntos
Biofilmes/crescimento & desenvolvimento , Escherichia coli Shiga Toxigênica/patogenicidade , Animais , Células CACO-2 , Linhagem Celular , Colicinas/metabolismo , Humanos , Escherichia coli Shiga Toxigênica/genética , Escherichia coli Shiga Toxigênica/isolamento & purificação , Escherichia coli Shiga Toxigênica/fisiologia , VirulênciaRESUMO
Thirty one out of 153 strains of Shigella sonnei isolated from Thai patients with diarrhoea showed antibacterial activity against S. sonnei by agar well diffusion method. All of them harbor plasmids with the genetic determination of colicin type 7 (Js) gene but without colicin E and colicin U gene. The PCR product obtained from strain 35/44 was shown to be the gene for colicin type 7 lytic protein (cja). The partially purified bacteriocin (PPB) containing colicin type 7 of strain 35/44 was prepared and used for characterization. The antibacterial activity of PPB against a total of 17 selected Gram-positive and Gram-negative bacteria was tested. It was found that PPB of strain 35/44 was active against E. coli O157, S. sonnei and S. boydii. The sensitivity of PPB from this strain to proteinase K, trypsin and -chymotrypsin suggests the proteinaceous nature of these antimicrobial substances. Therefore, this isolated bacterium can be regarded as bacteriocin producing bacteria. The bacteriocin produced by this isolated S. sonnei was heat stable as evidenced by its ability to maintain the activity at 80 °C for 60 min. In addition, it was stable within a wide range of pH (3-9). The molecular weight of colicin type 7 from isolated S. sonnei strain 35/44 analyzed by SDS-PAGE was 54.4 kDa composing of at least five subunits. It is to our knowledge, the first report of Thai patients with diarrhoea that S. sonnei isolated from them contained colicin type 7.(AU)
Assuntos
Shigella sonnei , Colicinas , Antibacterianos , BacteriocinasRESUMO
Thirty one out of 153 strains of Shigella sonnei isolated from Thai patients with diarrhoea showed antibacterial activity against S. sonnei by agar well diffusion method. All of them harbor plasmids with the genetic determination of colicin type 7 (Js) gene but without colicin E and colicin U gene. The PCR product obtained from strain 35/44 was shown to be the gene for colicin type 7 lytic protein (cja). The partially purified bacteriocin (PPB) containing colicin type 7 of strain 35/44 was prepared and used for characterization. The antibacterial activity of PPB against a total of 17 selected Gram-positive and Gram-negative bacteria was tested. It was found that PPB of strain 35/44 was active against E. coli O157, S. sonnei and S. boydii. The sensitivity of PPB from this strain to proteinase K, trypsin and α-chymotrypsin suggests the proteinaceous nature of these antimicrobial substances. Therefore, this isolated bacterium can be regarded as bacteriocin producing bacteria. The bacteriocin produced by this isolated S. sonnei was heat stable as evidenced by its ability to maintain the activity at 80 °C for 60 min. In addition, it was stable within a wide range of pH (3-9). The molecular weight of colicin type 7 from isolated S. sonnei strain 35/44 analyzed by SDS-PAGE was 54.4 kDa composing of at least five subunits. It is to our knowledge; the first report of Thai patients with diarrhoea that S. sonnei isolated from them contained colicin type 7.
Assuntos
Humanos , Colicinas/metabolismo , Disenteria Bacilar/microbiologia , Shigella sonnei/isolamento & purificação , Shigella sonnei/metabolismo , Colicinas/química , Colicinas/genética , Colicinas/isolamento & purificação , Eletroforese em Gel de Poliacrilamida , Bactérias Gram-Negativas/efeitos dos fármacos , Bactérias Gram-Positivas/efeitos dos fármacos , Concentração de Íons de Hidrogênio , Peso Molecular , Estabilidade Proteica , Proteólise , Plasmídeos/análise , Shigella sonnei/genética , Temperatura , TailândiaRESUMO
Thirty one out of 153 strains of Shigella sonnei isolated from Thai patients with diarrhoea showed antibacterial activity against S. sonnei by agar well diffusion method. All of them harbor plasmids with the genetic determination of colicin type 7 (Js) gene but without colicin E and colicin U gene. The PCR product obtained from strain 35/44 was shown to be the gene for colicin type 7 lytic protein (cja). The partially purified bacteriocin (PPB) containing colicin type 7 of strain 35/44 was prepared and used for characterization. The antibacterial activity of PPB against a total of 17 selected Gram-positive and Gram-negative bacteria was tested. It was found that PPB of strain 35/44 was active against E. coli O157, S. sonnei and S. boydii. The sensitivity of PPB from this strain to proteinase K, trypsin and α-chymotrypsin suggests the proteinaceous nature of these antimicrobial substances. Therefore, this isolated bacterium can be regarded as bacteriocin producing bacteria. The bacteriocin produced by this isolated S. sonnei was heat stable as evidenced by its ability to maintain the activity at 80 °C for 60 min. In addition, it was stable within a wide range of pH (3-9). The molecular weight of colicin type 7 from isolated S. sonnei strain 35/44 analyzed by SDS-PAGE was 54.4 kDa composing of at least five subunits. It is to our knowledge; the first report of Thai patients with diarrhoea that S. sonnei isolated from them contained colicin type 7.
Assuntos
Colicinas/metabolismo , Disenteria Bacilar/microbiologia , Shigella sonnei/isolamento & purificação , Shigella sonnei/metabolismo , Colicinas/química , Colicinas/genética , Colicinas/isolamento & purificação , Eletroforese em Gel de Poliacrilamida , Bactérias Gram-Negativas/efeitos dos fármacos , Bactérias Gram-Positivas/efeitos dos fármacos , Humanos , Concentração de Íons de Hidrogênio , Peso Molecular , Plasmídeos/análise , Estabilidade Proteica , Proteólise , Shigella sonnei/genética , Temperatura , TailândiaRESUMO
Entry of the peptide antibiotic microcin J25 (MccJ25) into target cells is mediated by the outer membrane receptor FhuA and the inner membrane protein SbmA. The latter also transports MccB17 into the cell cytoplasm. Comparison of MccJ25 and MccB17 revealed a tetrapeptide sequence (VGIG) common to both antibiotics. We speculated that this structural feature in MccJ25 could be a motif recognized by SbmA. To test this hypothesis, we used a MccJ25 variant in which the isoleucine in VGIG (position 13 in the MccJ25 sequence) was replaced by lysine (I13K). In experiments in which the FhuA receptor was bypassed, the substituted microcin showed an inhibitory activity similar to that of the wild-type peptide. Moreover, MccJ25 interfered with colicin M uptake by FhuA in a competition assay, while the I13K mutant did not. From these results, we propose that the Ile(13) residue is only required for interaction with FhuA, and that VGIG is not a major recognition element by SbmA.
Assuntos
Motivos de Aminoácidos , Antibacterianos/química , Antibacterianos/metabolismo , Proteínas da Membrana Bacteriana Externa/metabolismo , Bacteriocinas/química , Bacteriocinas/metabolismo , Proteínas de Escherichia coli/metabolismo , Isoleucina/química , Proteínas de Membrana Transportadoras/metabolismo , Substituição de Aminoácidos , Antibacterianos/farmacocinética , Bacteriocinas/genética , Bacteriocinas/farmacocinética , Colicinas/metabolismo , Colicinas/farmacocinética , Escherichia coli/efeitos dos fármacos , Escherichia coli/genética , Escherichia coli/metabolismo , Transporte Proteico , Relação Estrutura-Atividade , Especificidade por SubstratoRESUMO
Microcins are gene-encoded peptide antibiotics produced by enterobacteria that act on strains of gram-negative bacteria. In this work, we concentrated on higher-molecular-mass microcins, i.e., those possessing 60 or more amino acids. They can be subdivided into unmodified and posttranslationally modified peptides. In both cases, they exhibit conserved C-terminal sequences that appear to be characteristic of each subgroup. In the hypothesis that these sequences could correspond to domains, gene fusions between the activity genes for the unmodified microcin colicin V and the modified microcin H47 were constructed. These two microcins differ in their mode of synthesis, uptake, target, and specific immunity. Through this experimental approach, chimeric peptides with exchanged C-terminal sequences were encoded. Cells carrying the fusions in different genetic contexts were then assayed for antibiotic production. Many of them produced antibiotic activities with recombinant properties: the toxicity of one microcin and the mode of uptake of the other. The results led to the identification of a modular structure of colicin V and microcin H47, with the recognition of two domains in their peptide chains: a toxic N-terminal domain and an uptake C-terminal domain. This modular design would be shared by other microcins from each subgroup.
Assuntos
Antibacterianos/química , Bacteriocinas/química , Colicinas/química , Peptídeos/química , Sequência de Aminoácidos , Antibacterianos/biossíntese , Antibacterianos/farmacologia , Peptídeos Catiônicos Antimicrobianos , Bacteriocinas/biossíntese , Bacteriocinas/genética , Bacteriocinas/farmacologia , Colicinas/biossíntese , Colicinas/genética , Colicinas/imunologia , Colicinas/toxicidade , Sequência Conservada , Dissulfetos/química , Escherichia coli K12/genética , Fusão Gênica , Genes Bacterianos , Dados de Sequência Molecular , Peso Molecular , Testes do Emplastro , Peptídeos/genética , Peptídeos/imunologia , Peptídeos/metabolismo , Peptídeos/toxicidade , Plasmídeos , Precursores de Proteínas/química , Processamento de Proteína Pós-Traducional , Estrutura Terciária de Proteína , Receptores de Catecolaminas/genética , Receptores de Catecolaminas/metabolismo , Recombinação Genética , Homologia de Sequência de AminoácidosRESUMO
The aim of the study was to determine the occurrence of virulence genes expressing fimbriae, production of hemolysin, colicin and aerobactin among a hundred Escherichia coli isolates obtained from in-and outpatients of a tertiary-care teaching hospital, between July and August 2000, showing clinical and laboratory signs of urinary tract infection (UTI). The presence of genes (pap, afa, sfa) for fimbriae expression was assayed using specific primers in a polymerase chain reaction. Among the isolates studied, the prevalence of the virulence factors was 96.0%, 76.0%, 24.0%, for hemolysin, aerobactin and colicin, respectively; the prevalence of genes coding for fimbrial adhesive systems was 32.0%, 19.0% and 11.0% for pap, sfa and afa respectively. The strains isolated from the outpatients displayed a greater number of virulence factors compared to those from hospitalized subjects, emphasizing the difference between these two kinds of patients.
Assuntos
Infecções por Escherichia coli/microbiologia , Escherichia coli/patogenicidade , Infecções Urinárias/microbiologia , Fatores de Virulência/biossíntese , Adolescente , Adulto , Criança , Pré-Escolar , Colicinas/biossíntese , Infecções Comunitárias Adquiridas/microbiologia , Infecção Hospitalar/microbiologia , Escherichia coli/genética , Feminino , Fímbrias Bacterianas/genética , Proteínas Hemolisinas/biossíntese , Humanos , Ácidos Hidroxâmicos/análise , Lactente , Recém-Nascido , Masculino , Pessoa de Meia-Idade , Óperon/genética , Reação em Cadeia da Polimerase , Virulência , Fatores de Virulência/análise , Fatores de Virulência/genéticaRESUMO
The aim of the study was to determine the occurrence of virulence genes expressing fimbriae, production of hemolysin, colicin and aerobactin among a hundred Escherichia coli isolates obtained from in-and outpatients of a tertiary-care teaching hospital, between July and August 2000, showing clinical and laboratory signs of urinary tract infection (UTI). The presence of genes (pap, afa, sfa) for fimbriae expression was assayed using specific primers in a polymerase chain reaction. Among the isolates studied, the prevalence of the virulence factors was 96.0 percent, 76.0 percent, 24.0 percent, for hemolysin, aerobactin and colicin, respectively; the prevalence of genes coding for fimbrial adhesive systems was 32.0 percent, 19.0 percent and 11.0 percent for pap, sfa and afa respectively. The strains isolated from the outpatients displayed a greater number of virulence factors compared to those from hospitalized subjects, emphasizing the difference between these two kinds of patients.
O objetivo do trabalho foi determinar a ocorrência de fatores de virulência, tais como, a expressão de fímbrias, produção de hemolisina, colicina e aerobactina em 100 cepas de Escherichia coli isoladas de pacientes ambulatoriais e hospitalizados de um hospital universitário de nível de atendimento terciário, entre os meses de julho e agosto de 2000, que apresentavam sinais clínicos e laboratoriais de infecção do trato urinário (ITU). Foram pesquisados os genes pap, afa e sfa responsáveis pela expressão de fímbrias através da técnica de PCR. A freqüência dos fatores de virulência entre as cepas estudadas foi de 96,0 por cento, 76,0 por cento e 24,0 por cento para hemolisina, aerobactina e colicina respectivamente, e a prevalência dos genes para os sistemas de adesinas fimbriais foi de 32,0 por cento, 19,0 por cento e 11,0 por cento para os genes pap, sfa e afa respectivamente. As cepas isoladas dos pacientes ambulatoriais exibiram um número maior de fatores de virulência quando comparadas com aquelas provenientes de indivíduos hospitalizados.
Assuntos
Humanos , Masculino , Feminino , Recém-Nascido , Lactente , Pré-Escolar , Criança , Adolescente , Adulto , Pessoa de Meia-Idade , Infecções por Escherichia coli/microbiologia , Escherichia coli/patogenicidade , Ácidos Hidroxâmicos/análise , Infecções Urinárias/microbiologia , Fatores de Virulência/biossíntese , Colicinas/biossíntese , Infecções Comunitárias Adquiridas/microbiologia , Infecção Hospitalar/microbiologia , Escherichia coli/genética , Fímbrias Bacterianas/genética , Proteínas Hemolisinas/biossíntese , Óperon/genética , Reação em Cadeia da Polimerase , Virulência , Fatores de Virulência/análise , Fatores de Virulência/genéticaRESUMO
AIMS: The antagonistic activity of the Escherichia coli strain H22 against enteric bacteria was studied both in vitro and in vivo. METHODS AND RESULTS: In vitro, bacterial strains belonging to seven of nine genera of the family Enterobacteriaceae (Enterobacter, Escherichia, Klebsiella, Morganella, Salmonella, Shigella and Yersinia) were inhibited by the strain H22. Six days after simultaneous oral inoculation in germ-free mice, E. coli strain H22 reduced the faecal population of Shigella flexneri 4 to undetectable levels (P < 0.05). In ex vivo assay, inhibitory zones against Sh. flexneri 4 were observed around faecal samples from mice inoculated with E. coli strain H22. The in vitro inhibition of Sh. flexneri 4 was shown to be mediated by microcin C7. In addition to microcin C7, strain H22 was shown to produce aerobactin, new variants of colicins E1 and Ib, and bacteriophage particles with morphology similar to the phages of the family Myoviridae. CONCLUSIONS: Altogether, the properties of E. coli H22, observed both under in vitro and in vivo conditions, suggest its potential use as a probiotic strain for livestock and humans. SIGNIFICANCE AND IMPACT OF THE STUDY: The strain H22 was shown to produce several antimicrobial compounds with inhibitory capabilities against pathogenic or potentially pathogenic enterobacteria.
Assuntos
Enterobacteriaceae/fisiologia , Escherichia coli/fisiologia , Administração Oral , Animais , Antibacterianos/análise , Bacteriocinas/análise , Bacteriófagos/metabolismo , Colicinas/análise , Enterobacter/fisiologia , Escherichia/fisiologia , Fezes/microbiologia , Feminino , Ácidos Hidroxâmicos/análise , Klebsiella/fisiologia , Masculino , Camundongos , Microscopia Eletrônica/métodos , Morganella/fisiologia , Myoviridae , Plasmídeos/ultraestrutura , Salmonella/fisiologia , Shigella/fisiologia , Shigella flexneri/fisiologia , Sideróforos/análise , Yersinia/fisiologiaRESUMO
Xylella fastidiosa is the etiologic agent of diseases in a wide range of economically important crops including citrus variegated chlorosis, a major threat to the Brazilian citrus industry. The genomes of several strains of this phytopathogen have been completely sequenced enabling large-scale functional studies. In this work we used whole-genome DNA microarrays to investigate the transcription profile of X. fastidiosa grown in defined media with different glucose concentrations. Our analysis revealed that while transcripts related to fastidian gum production were unaffected, colicin-V-like and fimbria precursors were induced in high glucose medium. Based on these results, we suggest a model for colicin-defense mechanism in X. fastidiosa.
Assuntos
Regulação Bacteriana da Expressão Gênica , Genoma Bacteriano , Glucose/metabolismo , Xylella/genética , Sequência de Aminoácidos , Proliferação de Células , Clonagem Molecular , Colicinas/química , Colicinas/metabolismo , DNA Complementar/metabolismo , Fímbrias Bacterianas/metabolismo , Modelos Biológicos , Dados de Sequência Molecular , Hibridização de Ácido Nucleico , Análise de Sequência com Séries de Oligonucleotídeos , RNA Mensageiro/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Homologia de Sequência de Aminoácidos , Fatores de Tempo , Regulação para CimaRESUMO
Chromobacterium violaceum is a versatile, Gram-negative beta-protebacterium that grows in a variety of ecosystems in tropical and subtropical areas, such as the water and borders of the Negro River, in the Amazon region of Brazil. Although it is a saprophyte and is generally considered non-pathogenic, sporadic cases of human infection have been described, mainly in young children and in immunodeficient individuals. Although rare, infections with C. violaceum are characterized by rapid dissemination and high mortality. With the complete genome sequence of C. violaceum now available, a detailed description of the molecular arsenal required for this bacterium's remarkable versatility has been revealed. Most importantly, a more detailed picture of its biotechnological properties, including the characteristic violacein pigment, has emerged. The complete genome sequence also enabled us to make a thorough examination of the repertoire of genes encoding probable virulence factors, which determine the potential for pathogenesis. We described a number of genes involved in infectious processes, such as host cell adhesion, "contact-dependent secretion" of factors that promote cell invasion, as well as other virulence factors, such as cytolytic proteins. We also described genes involved with the synthesis of lipopolysaccharides and proteoglycan, known to elicit the synthesis of pro-inflammatory cytokines and involved in the detoxification process, which may contribute to the evasion of the bacteria from the host immune response.
Assuntos
Chromobacterium/genética , Genoma Bacteriano , Lipopolissacarídeos/biossíntese , Peptidoglicano/biossíntese , Fatores de Virulência/genética , Aderência Bacteriana/genética , Chromobacterium/patogenicidade , Colicinas/biossíntese , Colicinas/genética , Proteínas Hemolisinas/biossíntese , Proteínas Hemolisinas/genética , Indóis , Peptidoglicano/genética , Virulência/genéticaRESUMO
Chromobacterium violaceum is a versatile, Gram-negative beta-protebacterium that grows in a variety of ecosystems in tropical and subtropical areas, such as the water and borders of the Negro River, in the Amazon region of Brazil. Although it is a saprophyte and is generally considered non-pathogenic, sporadic cases of human infection have been described, mainly in young children and in immunodeficient individuals. Although rare, infections with C. violaceum are characterized by rapid dissemination and high mortality. With the complete genome sequence of C. violaceum now available, a detailed description of the molecular arsenal required for this bacterium's remarkable versatility has been revealed. Most importantly, a more detailed picture of its biotechnological properties, including the characteristic violacein pigment, has emerged. The complete genome sequence also enabled us to make a thorough examination of the repertoire of genes encoding probable virulence factors, which determine the potential for pathogenesis. We described a number of genes involved in infectious processes, such as host cell adhesion, [quot ]contact-dependent secretion[quot ] of factors that promote cell invasion, as well as other virulence factors, such as cytolytic proteins. We also described genes involved with the synthesis of lipopolysaccharides and proteoglycan, known to elicit the synthesis of pro-inflammatory cytokines and involved in the detoxification process, which may contribute to the evasion of the bacteria from the host immune response
Assuntos
Chromobacterium/genética , Fatores de Virulência/genética , Genoma Bacteriano , Lipopolissacarídeos/biossíntese , Aderência Bacteriana/genética , Chromobacterium/patogenicidade , Colicinas/biossíntese , Colicinas/genética , Proteínas Hemolisinas/biossíntese , Proteínas Hemolisinas/genética , Indóis , Virulência/genéticaRESUMO
The properties of colicin S8 are different for the cytoplasmic, periplasmic and extracellular protein. Interactions with its specific receptors reflect this. Active cell extracts separate into a non-anionic along with an anionic fraction by DEAE-Sephacell chromatography. Previously, we have purified cell-associated colicin S8 as an aggregation of highly related polypeptides; cytoplasmic colicin S8 seems to be post-translationally processed into an aggregation of polypeptides of molecular mass ranging from 45,000 Da to 60,000 Da. We suggest that a conformational change to colicin S8 may occur related to the export process.
Assuntos
Colicinas/metabolismo , Proteínas de Escherichia coli/metabolismo , Escherichia coli/metabolismo , Cromatografia por Troca Iônica , Colicinas/isolamento & purificação , Citoplasma/metabolismo , Espaço Extracelular/metabolismo , Transporte ProteicoRESUMO
An avian pathogenic Escherichia coli (APEC) strain designated SHS4, isolated from a chicken with clinical signs of swollen head syndrome (SHS), adhered to but did not invade Hep-2 and tracheal epithelial cells. The PCR amplified fimA, csgA and tsh gene sequences. It produced Ia, Ib, E1, E3, K, and B colicins, but not colicin V and aerobactin. It harboured two plasmids of 60 and 98MDa and was resistant to streptomycin and tetracycline. Conjugation with a nalidixic acid (Na) resistant K-12 recipient strain (MS101) showed that the 98MDa plasmid did not transfer, whereas transfer of the 60MDa plasmid resulted in concomitant transfer of adhesion to Hep-2 and tracheal epithelial cells, production of the colicins Ia, E1, E3, and K, and the tsh-related DNA sequence. Transposon (TnphoA) mutagenesis of strain TR4 gave rise to strain Mut23, which lost its adhesive capacities, but was still able to express the same colicins as did strain TR4. PCR was able to amplify the tsh-related DNA sequence in this strain and a molecular probe based on transposon TnphoA indicated that the transposon was inserted in the 60MDa plasmid. Based on these results, we suggest that the 60MDa plasmid have adhesion genes, which may be responsible for the initial colonization of the upper respiratory tract of chickens.
Assuntos
Adesinas de Escherichia coli/metabolismo , Aderência Bacteriana/fisiologia , Galinhas , Infecções por Escherichia coli/veterinária , Proteínas de Escherichia coli , Escherichia coli/fisiologia , Doenças das Aves Domésticas/microbiologia , Adesinas de Escherichia coli/química , Adesinas de Escherichia coli/genética , Animais , Proteínas de Bactérias/química , Proteínas de Bactérias/genética , Embrião de Galinha , Colicinas/metabolismo , Conjugação Genética/genética , DNA Bacteriano/química , DNA Bacteriano/genética , Escherichia coli/genética , Escherichia coli/isolamento & purificação , Escherichia coli/metabolismo , Infecções por Escherichia coli/microbiologia , Proteínas de Fímbrias/química , Proteínas de Fímbrias/genética , Hemaglutininas/química , Hemaglutininas/genética , Humanos , Ácidos Hidroxâmicos/metabolismo , Mutagênese Insercional , Plasmídeos/genética , Reação em Cadeia da Polimerase/veterinária , Células Tumorais CultivadasRESUMO
Sixty-three Escherichia coli strains isolated from broilers with respiratory problems were examined for virulence factors, hemolysin synthesis ability, motility, hemagglutination capacity, operon pap presence, colicin production, and serum resistance. The capacity to hemagglutinate guinea pig erythrocytes was found in 53 (84.1%) of the samples, but only 30 (47.6%) agglutinated chicken erythrocytes. D-mannose-sensitive hemagglutination against guinea pig erythrocytes was found in 19 (30.2%) samples and against chicken erythrocytes, in 15 (23.8%) samples, whereas the D-mannose-resistant hemagglutination with guinea pig erythrocytes was found in 34 (54%) samples, and 13 of these (20.6%) showed this characteristic against chicken erythrocytes. Operon pap, P fimbria codifier, was detected in 26 samples in a total of 34 D-mannose-resistant samples. Colicin production was observed in 55 (87.3%) of the strains, and 41.8% presented V colicin production. Of the samples analyzed, 56 (88.9%) presented serum resistance, six (9.5%) were intermediate, and only one (1.6%) was sensitive to the action of the complement. The diversity of virulence profiles detected in the samples in this study explains in part the multifactorial characteristics of avian colibacillosis.
Assuntos
Galinhas/microbiologia , Infecções por Escherichia coli/veterinária , Escherichia coli/patogenicidade , Doenças das Aves Domésticas/microbiologia , Infecções Respiratórias/veterinária , Animais , Brasil , Colicinas/biossíntese , Eritrócitos/imunologia , Escherichia coli/genética , Escherichia coli/isolamento & purificação , Infecções por Escherichia coli/microbiologia , Fímbrias Bacterianas/genética , Cobaias , Testes de Hemaglutinação/veterinária , Proteínas Hemolisinas/biossíntese , Reação em Cadeia da Polimerase/veterinária , Infecções Respiratórias/microbiologia , VirulênciaRESUMO
The colicins are protein compounds produced by, and active against, Escherichia coli and others members of Enterobacteriaceae family. At least 34 different colicins have been described and found to share an interesting number of features. In the present review we focus on the major characteristics of colicins of gram-negative bacteria and explore their production and practical applications.The colicins are protein compounds produced by, and active against, Escherichia coli and others members of Enterobacteriaceae family. At least 34 different colicins have been described and found to share an interesting number of features. In the present review we focus on the major characteristics of colicins of gram-negative bacteria and explore their production and practical applications
Assuntos
Colicinas , Enterobacteriaceae , Escherichia coli , Bactérias Gram-Negativas , Técnicas In Vitro , Evolução Biológica , EcologiaRESUMO
Microcin H47 is a gene-encoded peptide antibiotic produced by a natural Escherichia coli strain isolated in Uruguay. In order to identify cellular components necessary for its antibiotic action, microcin H47-resistant mutants isolated in this work, as well as previously described mutants affected in membrane proteins, were analyzed. These studies indicated that (i) receptor outer membrane proteins for ferric-catechol siderophores would be involved in microcin-specific binding to the cell surface, (ii) the TonB pathway is needed for microcin H47 uptake, and (iii) the presence of the ATP synthase complex is necessary for microcin action. The possibility that this last structure contains the antibiotic target is discussed.
Assuntos
Adenosina Trifosfatases/metabolismo , Antibacterianos/farmacologia , Escherichia coli/efeitos dos fármacos , Escherichia coli/genética , Peptídeos , Peptídeos Catiônicos Antimicrobianos , Bacteriófagos/genética , Clonagem Molecular , Colicinas/farmacologia , Meios de Cultura , DNA Bacteriano/química , DNA Bacteriano/genética , Plasmídeos/genéticaRESUMO
In order to detect phenotypic characteristics associated with pathogenicity, 25 strains of Escherichia coli, isolated from clinical cases of colisepticemia in broiler chickens, were examined to determine the following properties: colicinogenicity, colicin V production, type 1 fimbriae, hemolysin expression and motility. Colicinogenicity occurred in 72% of the strains, 56% of all strains produced colicin V, 84% were positive for type 1 fimbriae and 80% were positive for motility. None of the strains had hemolytic activity; however, all of them, expressed at least one of the other characteristics studied. These results suggest that the diversity of phenotypes detected partially explain the multifactorial nature of avian colisepticemia.
Assuntos
Infecções por Escherichia coli/veterinária , Escherichia coli/patogenicidade , Doenças das Aves Domésticas/microbiologia , Sepse/veterinária , Técnicas de Tipagem Bacteriana , Plasmídeos de Bacteriocinas , Técnicas Bacteriológicas , Colicinas/análise , Escherichia coli/isolamento & purificação , Infecções por Escherichia coli/microbiologia , Fímbrias Bacterianas/ultraestrutura , Técnica de Placa Hemolítica , México , Fenótipo , Sepse/microbiologia , VirulênciaRESUMO
The effects of pH and temperature on the stability of interdomain interactions of colicin B have been studied by differential-scanning calorimetry, circular dichroism, and fluorescence spectroscopy. The calorimetric properties were compared with those of the isolated pore-forming fragment. The unfolding profile of the full-length toxin is consistent with two endothermic transitions. Whereas peak A (T(m) = 55 degrees C) most likely corresponds to the receptor/translocation domain, peak B (T(m) = 59 degrees C) is associated with the pore-forming domain. By lowering the pH from 7 to 3.5, the transition temperature of peaks A and B are reduced by 25 and 18 degrees C, respectively, due to proton exchange upon denaturation. The isolated pore-forming fragment unfolds at much higher temperatures (T(m) = 65 degrees C) and is stable throughout a wide pH range, indicating that intramolecular interactions between the different colicin B domains result in a less stable protein conformation. In aqueous solution circular dichroism spectra have been used to estimate the content of helical secondary structure of colicin B ( approximately 40%) or its pore-forming fragment ( approximately 80%). Upon heating, the ellipticities at 222 nm strongly decrease at the transition temperature. In the presence of lipid vesicles the differential-scanning calorimetry profiles of the pore-forming fragment exhibit a low heat of transition multicomponent structure. The heat of transition of membrane-associated colicin B (T(m) = 54 degrees C at pH 3.5) is reduced and its secondary structure is conserved even at intermediate temperatures indicating incomplete unfolding due to strong protein-lipid interactions.
Assuntos
Colicinas/química , Bicamadas Lipídicas/metabolismo , Calorimetria , Dicroísmo Circular , Colicinas/metabolismo , Escherichia coli/metabolismo , Concentração de Íons de Hidrogênio , Conformação Proteica , Desnaturação Proteica , Dobramento de Proteína , Estrutura Secundária de Proteína , Estrutura Terciária de Proteína , Espectrometria de Fluorescência , Temperatura , TermodinâmicaRESUMO
In order to detect phenotypic characteristics associated with pathogenicity, 25 strains of Escherichia coli, isolated from clinical cases of colisepticemia in broiler chickens, were examined to determine the following properties: colicinogenicity, colicin V production, type 1 fimbriae, hemolysin expression and motility. Colicinogenicity occurred in 72 of the strains, 56 of all strains produced colicin V, 84 were positive for type 1 fimbriae and 80 were positive for motility. None of the strains had hemolytic activity; however, all of them, expressed at least one of the other characteristics studied. These results suggest that the diversity of phenotypes detected partially explain the multifactorial nature of avian colisepticemia.(AU)