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Evolution of Salmonella enterica serotype Typhimurium driven by anthropogenic selection and niche adaptation.

ABSTRACT: Salmonella enterica serotype Typhimurium (S. Typhimurium) is a leading cause of gastroenteritis and bacteraemia worldwide, and a model organism for the study of host-pathogen interactions. Two S. Typhimurium strains (SL1344 and ATCC14028) are widely used to study host-pathogen interactions, yet genotypic variation results in strains with diverse host range, pathogenicity and risk to food safety. The population structure of diverse strains of S. Typhimurium revealed a major phylogroup of predominantly sequence type 19 (ST19) and a minor phylogroup of ST36. The major phylogroup had a population structure with two high order clades (? and ?) and multiple subclades on extended internal branches, that exhibited distinct signatures of host adaptation and anthropogenic selection. Clade ? contained a number of subclades composed of strains from well characterized epidemics in domesticated animals, while clade ? contained multiple subclades associated with wild avian species. The contrasting epidemiology of strains in clade ? and ? was reflected by the distinct distribution of antimicrobial resistance (AMR) genes, accumulation of hypothetically disrupted coding sequences (HDCS), and signatures of functional diversification. These observations were consistent with elevated anthropogenic selection of clade ? lineages from adaptation to circulation in populations of domesticated livestock, and the predisposition of clade ? lineages to undergo adaptation to an invasive lifestyle by a process of convergent evolution with of host adapted Salmonella serotypes. Gene flux was predominantly driven by acquisition and recombination of prophage and associated cargo genes, with only occasional loss of these elements. The acquisition of large chromosomally-encoded genetic islands was limited, but notably, a feature of two recent pandemic clones (DT104 and monophasic S. Typhimurium ST34) of clade ? (SGI-1 and SGI-4).

SUBMITTER: Bawn M

PROVIDER: S-EPMC7302871 | biostudies-literature | 2020 Jun

REPOSITORIES: biostudies-literature

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Evolution of Salmonella enterica serotype Typhimurium driven by anthropogenic selection and niche adaptation.

Bawn Matt M Alikhan Nabil-Fareed NF Thilliez Gaëtan G Kirkwood Mark M Wheeler Nicole E NE Petrovska Liljana L Dallman Timothy J TJ Adriaenssens Evelien M EM Hall Neil N Kingsley Robert A RA

PLoS genetics 20200608 6

Salmonella enterica serotype Typhimurium (S. Typhimurium) is a leading cause of gastroenteritis and bacteraemia worldwide, and a model organism for the study of host-pathogen interactions. Two S. Typhimurium strains (SL1344 and ATCC14028) are widely used to study host-pathogen interactions, yet genotypic variation results in strains with diverse host range, pathogenicity and risk to food safety. The population structure of diverse strains of S. Typhimurium revealed a major phylogroup of predomin ...[more]

PMID: 32511244

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Project description:Regulation of flagellum biosynthesis is a hierarchical process that is tightly controlled to allow for efficient tuning of flagellar expression. Flagellum-mediated motility directs Salmonella enterica serovar Typhimurium toward the epithelial surface to enhance gut colonization, but flagella are potent activators of innate immune signaling, so fine-tuning flagellar expression is necessary for immune avoidance. In this work, we evaluate the role of the LysR transcriptional regulator YeiE in regulating flagellum-mediated motility. We show that yeiE is necessary and sufficient for swimming motility. A ΔyeiE mutant is defective for gut colonization in both the calf ligated ileal loop model and the murine colitis model due to its lack of motility. Expression of flagellar class 2 and 3 but not class 1 genes is reduced in the ΔyeiE mutant. We linked the motility dysregulation of the ΔyeiE mutant to repression of the anti-FlhD4C2 factor STM1697. Together, our results indicate that YeiE promotes virulence by enhancing cell motility, thereby providing a new regulatory control point for flagellar expression in Salmonella Typhimurium. IMPORTANCE The ability to finely tune virulence factor gene expression is required for bacterial pathogens to successfully colonize a host. Flagellum-mediated motility is critical for many gut pathogens to establish productive infections. However, flagella activate the immune system, leading to bacterial clearance; therefore, tight control of flagellar gene expression enhances bacterial fitness in the host. Here, we demonstrate that the transcriptional regulator YeiE acts as a control point for flagellar gene expression and is required for Salmonella Typhimurium to establish a productive infection in mammals. The expression of an inhibitor of flagellar biogenesis is repressed in the absence of yeiE. Our work adds a new layer to the tightly controlled cascade regulating control of flagellar gene expression to facilitate the fitness of an enteric pathogen.

Dataset Information

Evolution of Salmonella enterica serotype Typhimurium driven by anthropogenic selection and niche adaptation.

Publications

Evolution of Salmonella enterica serotype Typhimurium driven by anthropogenic selection and niche adaptation.

Similar Datasets

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