Dataset Information

OxyR-dependent formation of DNA methylation patterns in OpvABOFF and OpvABON cell lineages of Salmonella enterica.

ABSTRACT: Phase variation of the Salmonella enterica opvAB operon generates a bacterial lineage with standard lipopolysaccharide structure (OpvAB(OFF)) and a lineage with shorter O-antigen chains (OpvAB(ON)). Regulation of OpvAB lineage formation is transcriptional, and is controlled by the LysR-type factor OxyR and by DNA adenine methylation. The opvAB regulatory region contains four sites for OxyR binding (OBSA-D), and four methylatable GATC motifs (GATC1-4). OpvAB(OFF) and OpvAB(ON) cell lineages display opposite DNA methylation patterns in the opvAB regulatory region: (i) in the OpvAB(OFF) state, GATC1 and GATC3 are non-methylated, whereas GATC2 and GATC4 are methylated; (ii) in the OpvAB(ON) state, GATC2 and GATC4 are non-methylated, whereas GATC1 and GATC3 are methylated. We provide evidence that such DNA methylation patterns are generated by OxyR binding. The higher stability of the OpvAB(OFF) lineage may be caused by binding of OxyR to sites that are identical to the consensus (OBSA and OBSc), while the sites bound by OxyR in OpvAB(ON) cells (OBSB and OBSD) are not. In support of this view, amelioration of either OBSB or OBSD locks the system in the ON state. We also show that the GATC-binding protein SeqA and the nucleoid protein HU are ancillary factors in opvAB control.

SUBMITTER: Cota I

PROVIDER: S-EPMC4856963 | biostudies-literature | 2016 May

REPOSITORIES: biostudies-literature

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OxyR-dependent formation of DNA methylation patterns in OpvABOFF and OpvABON cell lineages of Salmonella enterica.

Cota Ignacio I Bunk Boyke B Spröer Cathrin C Overmann Jörg J König Christoph C Casadesús Josep J

Nucleic acids research 20151219 8

Phase variation of the Salmonella enterica opvAB operon generates a bacterial lineage with standard lipopolysaccharide structure (OpvAB(OFF)) and a lineage with shorter O-antigen chains (OpvAB(ON)). Regulation of OpvAB lineage formation is transcriptional, and is controlled by the LysR-type factor OxyR and by DNA adenine methylation. The opvAB regulatory region contains four sites for OxyR binding (OBSA-D), and four methylatable GATC motifs (GATC1-4). OpvAB(OFF) and OpvAB(ON) cell lineages displ ...[more]

PMID: 26687718

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Project description:BackgroundThe emergence of antimicrobial-resistant (AMR) strains of the important human and animal pathogen Salmonella enterica poses a growing threat to public health. Here, we studied the genome-wide evolution of 90 S. enterica AMR isolates, representing one host adapted serotype (S. Dublin) and two broad host range serotypes (S. Newport and S. Typhimurium).ResultsAMR S. Typhimurium had a large effective population size, a large and diverse genome, AMR profiles with high diversity, and frequent positive selection and homologous recombination. AMR S. Newport showed a relatively low level of diversity and a relatively clonal population structure. AMR S. Dublin showed evidence for a recent population bottleneck, and the genomes were characterized by a larger number of genes and gene ontology terms specifically absent from this serotype and a significantly higher number of pseudogenes as compared to other two serotypes. Approximately 50% of accessory genes, including specific AMR and putative prophage genes, were significantly over- or under-represented in a given serotype. Approximately 65% of the core genes showed phylogenetic clustering by serotype, including the AMR gene aac (6')-Iaa. While cell surface proteins were shown to be the main target of positive selection, some proteins with possible functions in AMR and virulence also showed evidence for positive selection. Homologous recombination mainly acted on prophage-associated proteins.ConclusionsOur data indicates a strong association between genome content of S. enterica and serotype. Evolutionary patterns observed in S. Typhimurium are consistent with multiple emergence events of AMR strains and/or ecological success of this serotype in different hosts or habitats. Evolutionary patterns of S. Newport suggested that antimicrobial resistance emerged in one single lineage, Lineage IIC. A recent population bottleneck and genome decay observed in AMR S. Dublin are congruent with its narrow host range. Finally, our results suggest the potentially important role of positive selection in the evolution of antimicrobial resistance, host adaptation and serotype diversification in S. enterica.

Dataset Information

OxyR-dependent formation of DNA methylation patterns in OpvABOFF and OpvABON cell lineages of Salmonella enterica.

Publications

OxyR-dependent formation of DNA methylation patterns in OpvABOFF and OpvABON cell lineages of Salmonella enterica.

Similar Datasets

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