RESUMEN
Xeroderma pigmentosum variant (XP-V) is an autosomal recessive disease with an increased risk of developing cutaneous neoplasms in sunlight-exposed regions. These cells are deficient in the translesion synthesis (TLS) DNA polymerase eta, responsible for bypassing different types of DNA lesions. From the exome sequencing of 11 skin tumors of a genetic XP-V patients' cluster, classical mutational signatures related to sunlight exposure, such as C>T transitions targeted to pyrimidine dimers, were identified. However, basal cell carcinomas also showed distinct C>A mutation spectra reflecting a mutational signature possibly related to sunlight-induced oxidative stress. Moreover, four samples carry different mutational signatures, with C>A mutations associated with tobacco chewing or smoking usage. Thus, XP-V patients should be warned of the risk of these habits. Surprisingly, higher levels of retrotransposon somatic insertions were also detected when the tumors were compared with non-XP skin tumors, revealing other possible causes for XP-V tumors and novel functions for the TLS polymerase eta in suppressing retrotransposition. Finally, the expected high mutation burden found in most of these tumors renders these XP patients good candidates for checkpoint blockade immunotherapy.
Asunto(s)
Neoplasias Cutáneas , Xerodermia Pigmentosa , Humanos , Xerodermia Pigmentosa/genética , Retroelementos/genética , Mutación , Reparación del ADN , Neoplasias Cutáneas/genética , Rayos Ultravioleta/efectos adversosRESUMEN
The recessive mutant mice bate palmas (bapa) - claps in Portuguese arose from N-ethyl-N-nitrosourea mutagenesis. A single nucleotide, T > C, change in exon 13, leading to a Thr1289 Ala substitution, was identified in the lysine (K)-specific methyltransferase 2D gene (Kmt2d) located on chromosome 15. Mutations with a loss-of-function in the KMT2D gene on chromosome 12 in humans are responsible for Kabuki syndrome (KS). Phenotypic characterization of the bapa mutant was performed using a behavioral test battery to evaluate the parameters related to general activity, the sensory nervous system, the psychomotor system, and the autonomous nervous system, as well as to measure motor function and spatial memory. Relative to BALB/cJ mice, the bapa mutant showed sensory and psychomotor impairments, such as hypotonia denoted by a surface righting reflex impairment and hindquarter fall, and a reduction in the auricular reflex, suggesting hearing impairment. Additionally, the enhanced general activity showed by the increased rearing and grooming frequency, distance traveled and average speed possibly presupposes the presence of hyperactivity of bapa mice compared with the control group. A slight motor coordination dysfunction was showed in bapa mice, which had a longer crossing time on the balance beam compared with BALB/cJ controls. Male bapa mice also showed spatial gait pattern changes, such as a shorter stride length and shorter step length. In conclusion, the bapa mouse may be a valuable animal model to study the mechanisms involved in psychomotor and behavior impairments, such as hypotonia, fine motor coordination and hyperactivity linked to the Kmt2d mutation.
Asunto(s)
Anomalías Múltiples/genética , Conducta Animal , Cara/anomalías , Enfermedades Hematológicas/genética , N-Metiltransferasa de Histona-Lisina/genética , Mutación con Pérdida de Función , Proteína de la Leucemia Mieloide-Linfoide/genética , Enfermedades Vestibulares/genética , Anomalías Múltiples/fisiopatología , Animales , Modelos Animales de Enfermedad , Cara/fisiopatología , Marcha , Audición , Enfermedades Hematológicas/fisiopatología , Masculino , Ratones , Ratones Endogámicos BALB C , Movimiento , Hipotonía Muscular/genética , Reflejo , Enfermedades Vestibulares/fisiopatologíaRESUMEN
OBJECTIVES: KPC-producing Klebsiella pneumoniae is considered one of the most worrisome multidrug-resistant micro-organisms in nosocomial infections. It has also been reported in wastewater and urban rivers in the city of Sao Paulo, Brazil. Here we report the draft genome sequences of three KPC-2- and CTX-M-15-producing K. pneumoniae sequence type 437 (ST437) isolates obtained from two urban rivers and from a clinical sample of a patient in Sao Paulo. METHODS: A genomic library was constructed using a Nextera XT Kit. An Illumina platform was used to perform whole-genome sequencing (WGS). RESULTS: WGS of environmental isolates Kp148/PINH-4900 and Kp196/TIET-4200 and clinical isolate Kp314/11 resulted in estimated genome sizes of 5464058, 5437723 and 5319218bp, respectively. Resistome analysis of the environmental and clinical strains revealed the presence of resistance genes to the following antimicrobials in all strains: aminoglycosides [aac(6')-Ib-cr]; ß-lactams (blaOXA-1, blaSHV-11, blaCTX-M-15 and blaKPC-2); fluoroquinolones [aac(6')-Ib-cr, oqxA and oqxB]; fosfomycin (fosAKP); macrolides [mph(A)]; phenicols (catB4); sulfonamides (sul1); and trimethoprim (dfrA30). The tetracycline resistance gene tetA was identified in Kp148/PINH-4900 and Kp314/11 only; the aminoglycoside resistance gene aph(3')-Ia was found only in environmental isolates, and aadA2 only in Kp314/11; and the phenicol resistance gene catA1 was identified only in Kp148/PINH-4900. CONCLUSIONS: The draft genome sequences of these strains help us to elucidate the dissemination of resistance genes in micro-organisms inside and outside the hospital and are useful for further comparisons between clinical and environmental strains.
Asunto(s)
Genoma Bacteriano , Infecciones por Klebsiella/microbiología , Klebsiella pneumoniae/genética , Parques Recreativos , Ríos/microbiología , Antibacterianos/farmacología , Técnicas de Tipificación Bacteriana , Brasil , Farmacorresistencia Bacteriana Múltiple , Humanos , Klebsiella pneumoniae/clasificación , Klebsiella pneumoniae/efectos de los fármacos , Klebsiella pneumoniae/enzimología , Pruebas de Sensibilidad Microbiana , Tipificación de Secuencias Multilocus , Análisis de Secuencia de ADN , Secuenciación Completa del Genoma , beta-Lactamasas/genéticaRESUMEN
OBJECTIVES: Marine bivalves can act as bioindicators of marine environment pollution by multidrug-resistant (MDR) enteric bacteria of medical interest. The aim of this study was to report the draft genome sequence of a plasmid-encoded AmpC (pAmpC) (CMY-2)-carrying Escherichia coli isolate recovered from a marine bivalve sample in the coastal shore of Southeast Brazil. METHODS: The whole genome was sequenced on an Illumina NextSeq platform and was assembled using Velvet v.1.2.10. Data analysis was carried out using tools available from the Center of Genomic Epidemiology and Geneious R10 software. RESULTS: The genome size was calculated at 5198055bp, comprising a total of 5316 protein-coding sequences. The strain was assigned to ST457 and presented the blaCMY-2 pAmpC gene. In addition, the strain was clustered into the pathogenic phylogenetic group D. CONCLUSION: The release of this draft genome sequence can provide valuable information to better understand the dissemination of MDR enteric bacteria in marine environments.
Asunto(s)
Bivalvos/microbiología , Farmacorresistencia Bacteriana Múltiple , Escherichia coli/genética , Genoma Bacteriano , Animales , Proteínas Bacterianas/genética , Brasil , Escherichia coli/aislamiento & purificación , Infecciones por Escherichia coli/microbiología , Filogenia , Plásmidos/genética , Análisis de Secuencia de ADN , Secuenciación Completa del Genoma , beta-Lactamasas/genéticaRESUMEN
The emergence of hypervirulent Klebsiella pneumoniae (hvKP) with multidrug resistance (MDR) profile is a worrisome public health issue. We report the first draft genome sequence of a hypermucoviscous (positive string test) and MDR K. pneumoniae serotype K19, belonging to ST29, isolated from human infection. This strain harboured multiple antimicrobial resistance genes, including blaCTX-M-15, besides yersiniabactin and type 3 fimbriae virulence genes. In vivo experiments carried out with the Galleria mellonella infection model revealed that K. pneumoniae K19/ST29 killed 100% of the larvae at 24 h post-infection, in a similar way to the known hypermucoviscous hvKP K1/ST23 lineage.
Asunto(s)
Genoma Bacteriano , Infecciones por Klebsiella/microbiología , Klebsiella pneumoniae/enzimología , Klebsiella pneumoniae/genética , Análisis de Secuencia de ADN , beta-Lactamasas/metabolismo , Animales , Modelos Animales de Enfermedad , Farmacorresistencia Bacteriana Múltiple , Humanos , Klebsiella pneumoniae/aislamiento & purificación , Larva/microbiología , Larva/fisiología , Lepidópteros/microbiología , Lepidópteros/fisiología , Masculino , Persona de Mediana Edad , Análisis de Supervivencia , Virulencia , Factores de Virulencia/genéticaRESUMEN
OBJECTIVES: Multidrug-resistant (MDR) Enterobacter aerogenes strains are frequently associated with nosocomial infections and high mortality rates, representing a serious public health problem. The aim of this study was to present the draft genome sequence of a MDR KPC-2-producing E. aerogenes isolated from a perineal swab of a hospitalised patient in Brazil. METHODS: Genomic DNA was sequenced using an Illumina MiSeq platform. De novo genome assembly was carried out using the A5-Miseq pipeline, and whole-genome sequence analysis was performed using tools from the Center for Genomic Epidemiology. RESULTS: The strain harboured resistance genes to ß-lactams, aminoglycosides, sulphonamides and trimethoprim in addition to genes encoding multidrug efflux system proteins, a quaternary ammonium transporter and heavy metal efflux system proteins. In addition, the strain harboured genes encoding diverse virulence factors. CONCLUSION: These data might allow a better understanding of the genetic basis of antimicrobial resistance and virulence in E. aerogenes strains.
Asunto(s)
Farmacorresistencia Bacteriana Múltiple , Enterobacter aerogenes/aislamiento & purificación , Infecciones por Enterobacteriaceae/microbiología , Secuenciación Completa del Genoma/métodos , Brasil , Enterobacter aerogenes/genética , Genoma Bacteriano , Secuenciación de Nucleótidos de Alto Rendimiento , Hospitalización , Humanos , Factores de Virulencia/genéticaRESUMEN
OBJECTIVES: Aquatic environments have contributed to the dissemination of multidrug-resistant (MDR) bacteria, representing a risk for humans and animals. The aim of this study was to report the first draft genome sequence of a MDR Enterobacter cloacae strain recovered from seawater in a public beach in Brazil. METHODS: The genome was sequenced on an Illumina MiSeq platform. De novo genome assembly was performed using SPAdes 3.10.1 and the whole genome sequence was analysed using bioinformatics tools from the Center of Genomic Epidemiology. RESULTS: This draft genome resulted in 5 228 857bp with 5331 protein-coding sequences, revealing the presence of blaKPC-2, blaCTX-M-15 and blaOXA-17 genes, responsible for resistance to all ß-lactam antibiotics. In addition, the strain was assigned to sequenced type 520 (ST520). CONCLUSION: These data provide useful information for comparative genomic analysis regarding the dissemination of antibiotic resistance genes.
Asunto(s)
Farmacorresistencia Bacteriana Múltiple , Enterobacter cloacae/clasificación , Secuenciación Completa del Genoma/métodos , beta-Lactamasas/genética , Océano Atlántico , Proteínas Bacterianas/genética , Técnicas de Tipificación Bacteriana , Playas , Brasil , Enterobacter cloacae/genética , Genoma Bacteriano , Tipificación de Secuencias Multilocus , Microbiología del AguaRESUMEN
Escherichia coli, the main host of the CTX-M-15 extended-spectrum ß-lactamase (ESBL) enzyme, is widely distributed and exchanged between the environment, animals and humans. Therefore, identification of blaCTX-M-15-positive lineages in food has a significant impact on public health. In this regard, until the end of 1990s, ESBL-producing isolates were mainly associated with hospital-acquired infections, with a predominance of SHV- and TEM-type enzymes. In recent years, a new trend has been observed among ESBL-producers, where most isolates now harbour CTX-M-type, being further isolated from community-acquired infections. Nowadays, CTX-M-15 has been recognised as the most important ESBL variant, invading virtually all human and animal compartments, leading to a global pandemic. Thus, whilst the rapid emergence and dissemination of CTX-M-15 among E. coli isolates has generated a large genetic reservoir from which other members of the Enterobacteriaceae family can easily acquire this resistance gene, there are an increasing number of new reservoirs and transmission mechanisms that must be investigated. In this study, we present the draft genome sequence of a CTX-M-15-producing E. coli ST345 isolated from commercial chicken meat in Brazil. This draft genome can be used as a reference sequence for comparative analysis among CTX-M-15-producers.
Asunto(s)
Escherichia coli/genética , Escherichia coli/aislamiento & purificación , Genoma Bacteriano , Carne/microbiología , Análisis de Secuencia de ADN , Secuenciación Completa del Genoma , beta-Lactamasas/metabolismo , Animales , Brasil , Pollos , Farmacorresistencia Bacteriana , Escherichia coli/enzimología , Genes Bacterianos , Anotación de Secuencia MolecularRESUMEN
Anthropogenic activities, including the release of wastewater and sewage from hospitals, have contributed to the contamination of aquatic environments, raising a concern to public health. In this study, we present the first draft genome sequence of a Klebsiella pneumoniae strain (Kp171, TIET-4200) belonging to the high-risk hospital-associated clonal lineage ST340/CC258, which was recovered from a water sample collected in an urban river in Brazil.
Asunto(s)
Farmacorresistencia Bacteriana Múltiple , Genoma Bacteriano , Klebsiella pneumoniae/genética , Ríos/microbiología , Análisis de Secuencia de ADN , Brasil , Ciudades , Genotipo , Klebsiella pneumoniae/clasificación , Klebsiella pneumoniae/aislamiento & purificación , Tipificación MolecularRESUMEN
Cystic fibrosis (CF) patients are often chronically colonised or infected by non-fermenting Gram-negative bacilli, with Pseudomonas aeruginosa being the most prevalent. In this study, we report the draft genome sequence of a multidrug-resistant P. aeruginosa strain belonging to sequence type ST235, isolated from the respiratory tract of a CF patient with chronic colonisation. Whole-genome sequencing analysis revealed a 6.7Mb genome size and the presence of 12 antibiotic resistance genes, including the rmtG gene conferring high-level aminoglycoside resistance, located on the chromosome.
Asunto(s)
Genoma Bacteriano , Pseudomonas aeruginosa/genética , Análisis de Secuencia de ADN , Secuenciación Completa del Genoma , Aminoglicósidos/farmacología , Antibacterianos/farmacología , Fibrosis Quística/complicaciones , Farmacorresistencia Bacteriana , Genes Bacterianos , Humanos , Infecciones por Pseudomonas/microbiología , Pseudomonas aeruginosa/efectos de los fármacos , Pseudomonas aeruginosa/aislamiento & purificaciónAsunto(s)
Pollos/microbiología , Farmacorresistencia Bacteriana Múltiple/genética , Carne/microbiología , Salmonella enterica/genética , Salmonella enterica/aislamiento & purificación , Serogrupo , beta-Lactamasas/genética , Animales , Antibacterianos/farmacología , Proteínas Bacterianas/genética , Brasil , ADN Bacteriano/análisis , Farmacorresistencia Bacteriana Múltiple/efectos de los fármacos , Genes Bacterianos/genética , Tamaño del Genoma , Genoma Bacteriano , Pruebas de Sensibilidad Microbiana , Tipificación de Secuencias Multilocus , Filogenia , Salmonella enterica/clasificación , Salmonella enterica/efectos de los fármacos , Secuenciación Completa del Genoma/métodosRESUMEN
Klebsiella pneumoniae carrying blaCTX-M-15 have been widely disseminated in hospital settings. In this regard, most clinically important strains belong to clonal complex 28 (CC258), which includes sequence type 340 (ST340). In this study, we present the draft genome sequence of a CTX-M-15-producing ST340 K. pneumoniae strain isolated from a food-producing animal in Brazil.
Asunto(s)
Genoma Bacteriano , Klebsiella pneumoniae/genética , beta-Lactamasas/genética , Animales , Brasil , Infecciones por Klebsiella/veterinaria , Klebsiella pneumoniae/enzimología , Porcinos/microbiología , Enfermedades de los Porcinos/microbiologíaRESUMEN
Previously we have characterized the complete gene encoding a pyruvate decarboxylase (PDC)/indolepyruvate decarboxylase (IPDC) of Phytomonas serpens, a trypanosomatid highly abundant in tomato fruits. Phylogenetic analyses indicated that the clade that contains the trypanosomatid protein behaves as a sister group of IPDCs of γ-proteobacteria. Since IPDCs are key enzymes in the biosynthesis of the plant hormone indole-3-acetic acid (IAA), the ability for IAA production by P. serpens was investigated. Similar to many microorganisms, the production of IAA and related indolic compounds, quantified by high performance liquid chromatography, increased in P. serpens media in response to amounts of tryptophan. The auxin functionality was confirmed in the hypocotyl elongation assay. In tomato fruits inoculated with P. serpens the concentration of free IAA had no significant variation, whereas increased levels of IAA-amide and IAA-ester conjugates were observed. The data suggest that the auxin produced by the flagellate is converted to IAA conjugates, keeping unaltered the concentration of free IAA. Ethanol also accumulated in P. serpens-conditioned media, as the result of a PDC activity. In the article we discuss the hypothesis of the bifunctionality of P. serpens PDC/IPDC and provide a three-dimensional model of the enzyme.
Asunto(s)
Carboxiliasas/metabolismo , Frutas/parasitología , Ácidos Indolacéticos/metabolismo , Solanum lycopersicum/parasitología , Trypanosomatina/enzimología , Secuencia de Aminoácidos , Carboxiliasas/genética , Homeostasis , Interacciones Huésped-Parásitos , Ácidos Indolacéticos/química , Modelos Estructurales , Datos de Secuencia Molecular , Filogenia , Proteínas Protozoarias/genética , Proteínas Protozoarias/metabolismo , Alineación de Secuencia , Trypanosomatina/genética , Trypanosomatina/fisiologíaRESUMEN
Nucleotide excision repair (NER) is the most flexible of all known DNA-repair mechanisms, and XPG is a 3'-endonuclease that participates in NER. Mutations in this gene (ERCC5) may result in the human syndrome xeroderma pigmentosum (XP) and, in some cases, in the complex phenotype of Cockayne syndrome (CS). Two Brazilian XP siblings, who were mildly affected, were investigated and classified into the XP-G group. The cells from these patients were highly ultraviolet (UV) sensitive but not sensitive to photosensitized methylene blue, an agent that causes oxidative stress. This phenotype is in contrast to XP-G/CS cells, which are highly sensitive to this oxidative agent. Sequencing revealed a compound heterozygous genotype with two novel missense mutations: c.83C>A (p.Ala28Asp) and c.2904G>C (p.Trp968Cys). The first mutation maps to the catalytic site of the XPG protein, whereas the second may compromise binding to DNA. Functional assays indicated that the mutated alleles were unable to perform the complete repair of UV-irradiated plasmids; however, full correction was observed for oxidatively damaged plasmids. Therefore, the XP phenotype of these patients is caused by novel missense mutations that specifically affect DNA repair for UV- but not oxidative-stress-induced DNA damage, and implications for XP versus XP/CS phenotype are discussed.
Asunto(s)
Supervivencia Celular/efectos de la radiación , Reparación del ADN/efectos de la radiación , Proteínas de Unión al ADN/genética , Endonucleasas/genética , Proteínas Nucleares/genética , Factores de Transcripción/genética , Adolescente , Alelos , Secuencia de Aminoácidos , Brasil , Línea Celular , Clonación Molecular , Síndrome de Cockayne/genética , Daño del ADN/efectos de la radiación , Femenino , Fibroblastos/citología , Fibroblastos/efectos de la radiación , Heterocigoto , Humanos , Masculino , Datos de Secuencia Molecular , Mutación Missense , Estrés Oxidativo/efectos de la radiación , Fenotipo , Conformación Proteica , Alineación de Secuencia , Análisis de Secuencia de ADN , Rayos Ultravioleta , Xerodermia Pigmentosa/genética , Adulto JovenRESUMEN
Winged-helix transcriptional factors play important roles in the control of gene expression in many organisms. In the plant pathogens Xylella fastidiosa and Agrobacterium tumefaciens, the winged-helix protein BigR, a member of the ArsR/SmtB family of metal sensors, regulates transcription of the bigR operon involved in bacterial biofilm growth. Previous studies showed that BigR represses transcription of its own operon through the occupation of the RNA polymerase-binding site; however, the signals that modulate its activity and the biological function of its operon are still poorly understood. Here we show that although BigR is a homodimer similar to metal sensors, it functions as a novel redox switch that derepresses transcription upon oxidation. Crystal structures of reduced and oxidized BigR reveal that formation of a disulfide bridge involving two critical cysteines induces conformational changes in the dimer that remarkably alter the topography of the winged-helix DNA-binding interface, precluding DNA binding. This structural mechanism of DNA association-dissociation is novel among winged-helix factors. Moreover, we demonstrate that the bigR operon is required for hydrogen sulfide detoxification through the action of a sulfur dioxygenase (Blh) and sulfite exporter. As hydrogen sulfide strongly inhibits cytochrome c oxidase, it must be eliminated to allow aerobic growth under low oxygen tension, an environmental condition found in bacterial biofilms, xylem vessels, and root tissues. Accordingly, we show that the bigR operon is critical to sustain bacterial growth under hypoxia. These results suggest that BigR integrates the transcriptional regulation of a sulfur oxidation pathway to an oxidative signal through a thiol-based redox switch.