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Functional analysis of colonization factor antigen I positive enterotoxigenic Escherichia coli identifies genes implicated in survival in water and host colonization.

ABSTRACT: Enterotoxigenic Escherichia coli (ETEC) expressing the colonization pili CFA/I are common causes of diarrhoeal infections in humans. Here, we use a combination of transposon mutagenesis and transcriptomic analysis to identify genes and pathways that contribute to ETEC persistence in water environments and colonization of a mammalian host. ETEC persisting in water exhibit a distinct RNA expression profile from those growing in richer media. Multiple pathways were identified that contribute to water survival, including lipopolysaccharide biosynthesis and stress response regulons. The analysis also indicated that ETEC growing in vivo in mice encounter a bottleneck driving down the diversity of colonizing ETEC populations.

SUBMITTER: Abd El Ghany M

PROVIDER: S-EPMC8461466 | biostudies-literature | 2021 Jun

REPOSITORIES: biostudies-literature

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Functional analysis of colonization factor antigen I positive enterotoxigenic <i>Escherichia coli</i> identifies genes implicated in survival in water and host colonization.

Abd El Ghany Moataz M Barquist Lars L Clare Simon S Brandt Cordelia C Mayho Matthew M Joffre Enrique E Sjöling Åsa Å Turner A Keith AK Klena John D JD Kingsley Robert A RA Hill-Cawthorne Grant A GA Dougan Gordon G Pickard Derek D

Microbial genomics 20210601 6

Enterotoxigenic <i>Escherichia coli</i> (ETEC) expressing the colonization pili CFA/I are common causes of diarrhoeal infections in humans. Here, we use a combination of transposon mutagenesis and transcriptomic analysis to identify genes and pathways that contribute to ETEC persistence in water environments and colonization of a mammalian host. ETEC persisting in water exhibit a distinct RNA expression profile from those growing in richer media. Multiple pathways were identified that contribute ...[more]

PMID: 34110281

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Project description:UnlabelledIron availability functions as an environmental cue for enteropathogenic bacteria, signaling arrival within the human host. As enterotoxigenic Escherichia coli (ETEC) is a major cause of human diarrhea, the effect of iron on ETEC virulence factors was evaluated here. ETEC pathogenicity is directly linked to production of fimbrial colonization factors and secretion of heat-labile enterotoxin (LT) and/or heat-stable enterotoxin (ST). Efficient colonization of the small intestine further requires at least the flagellin binding adhesin EtpA. Under iron starvation, production of the CFA/I fimbriae was increased in the ETEC H10407 prototype strain. In contrast, LT secretion was inhibited. Furthermore, under iron starvation, gene expression of the cfa (CFA/I) and etp (EtpBAC) operons was induced, whereas transcription of toxin genes was either unchanged or repressed. Transcriptional reporter fusion experiments focusing on the cfa operon further showed that iron starvation stimulated cfaA promoter activity in ETEC, indicating that the impact of iron on CFA/I production was mediated by transcriptional regulation. Evaluation of cfaA promoter activity in heterologous E. coli single mutant knockout strains identified IscR as the regulator responsible for inducing cfa fimbrial gene expression in response to iron starvation, and this was confirmed in an ETEC ΔiscR strain. The global iron response regulator, Fur, was not implicated. IscR binding sites were identified in silico within the cfaA promoter and fixation confirmed by DNase I footprinting, indicating that IscR directly binds the promoter region to induce CFA/I.ImportancePathogenic enterobacteria modulate expression of virulence genes in response to iron availability. Although the Fur transcription factor represents the global regulator of iron homeostasis in Escherichia coli, we show that several ETEC virulence factors are modulated by iron, with expression of the major fimbriae under the control of the iron-sulfur cluster regulator, IscR. Furthermore, we demonstrate that the apo form of IscR, lacking an Fe-S cluster, is able to directly fix the corresponding promoter region. These results provide further evidence implicating IscR in bacterial virulence and suggest that IscR may represent a more general regulator mediating the iron response in enteropathogens.

Dataset Information

Functional analysis of colonization factor antigen I positive enterotoxigenic Escherichia coli identifies genes implicated in survival in water and host colonization.

Publications

Functional analysis of colonization factor antigen I positive enterotoxigenic <i>Escherichia coli</i> identifies genes implicated in survival in water and host colonization.

Similar Datasets

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