Dataset Information

Variation of intragenic tandem repeat tract of tolA modulates Escherichia coli stress tolerance.

ABSTRACT: In recent work we discovered that the intragenic tandem repeat (TR) region of the tolA gene is highly variable among different Escherichia coli strains. The aim of this study was therefore to investigate the biological function and dynamics of TR variation in E. coli tolA. The biological impact of TR variation was examined by comparing the ability of a set of synthetic tolA variants with in frame repeat copies varying from 2 to 39 to rescue the altered susceptibility of an E. coli ?tolA mutant to deoxycholic acid, sodium dodecyl sulfate, hyperosmolarity, and infection with filamentous bacteriophage. Interestingly, although each of the TolA variants was able to at least partly rescue the ?tolA mutant, the extent was clearly dependent on both the repeat number and the type of stress imposed, indicating the existence of opposing selective forces with regard to the optimal TR copy number. Subsequently, TR dynamics in a clonal population were assayed, and we could demonstrate that TR contractions are RecA dependent and enhanced in a DNA repair deficient uvrD background, and can occur at a frequency of 6.9×10(-5).

SUBMITTER: Zhou K

PROVIDER: S-EPMC3477136 | biostudies-literature | 2012

REPOSITORIES: biostudies-literature

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Variation of intragenic tandem repeat tract of tolA modulates Escherichia coli stress tolerance.

Zhou Kai K Michiels Chris W CW Aertsen Abram A

PloS one 20121019 10

In recent work we discovered that the intragenic tandem repeat (TR) region of the tolA gene is highly variable among different Escherichia coli strains. The aim of this study was therefore to investigate the biological function and dynamics of TR variation in E. coli tolA. The biological impact of TR variation was examined by comparing the ability of a set of synthetic tolA variants with in frame repeat copies varying from 2 to 39 to rescue the altered susceptibility of an E. coli ΔtolA mutant t ...[more]

PMID: 23094082

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Project description:Due to the potential of enterohemorrhagic Escherichia coli (EHEC) serogroup O157 to cause large food borne outbreaks, national and international surveillance is necessary. For developing an effective method of molecular surveillance, a conventional method, multilocus variable-number tandem-repeat analysis (MLVA), and whole-genome sequencing (WGS) analysis were compared. WGS of 369 isolates of EHEC O157 belonging to 7 major MLVA types and their relatives were subjected to comprehensive in silico typing, core genome single nucleotide polymorphism (cgSNP), and core genome multilocus sequence typing (cgMLST) analyses. The typing resolution was the highest in cgSNP analysis. However, determination of the sequence of the mismatch repair protein gene mutS is necessary because spontaneous deletion of the gene could lead to a hypermutator phenotype. MLVA had sufficient typing resolution for a short-term outbreak investigation and had advantages in rapidity and high throughput. cgMLST showed less typing resolution than cgSNP, but it is less time-consuming and does not require as much computer power. Therefore, cgMLST is suitable for comparisons using large data sets (e.g., international comparison using public databases). In conclusion, screening using MLVA followed by cgMLST and cgSNP analyses would provide the highest typing resolution and improve the accuracy and cost-effectiveness of EHEC O157 surveillance.IMPORTANCE Intensive surveillance for enterohemorrhagic Escherichia coli (EHEC) serogroup O157 is important to detect outbreaks and to prevent the spread of the bacterium. Recent advances in sequencing technology made molecular surveillance using whole-genome sequence (WGS) realistic. To develop rapid, high-throughput, and cost-effective typing methods for real-time surveillance, typing resolution of WGS and a conventional typing method, multilocus variable-number tandem-repeat analysis (MLVA), was evaluated. Nation-level systematic comparison of MLVA, core genome single nucleotide polymorphism (cgSNP), and core genome multilocus sequence typing (cgMLST) indicated that a combination of WGS and MLVA is a realistic approach to improve EHEC O157 surveillance.

Project description:In the present study, it is shown that although Escherichia coli CFT073, a human uropathogenic (UPEC) strain, grows in liquid glucose M9 minimal medium, it fails to grow on glucose M9 minimal medium agar plates seeded with ?10(6) CFU. The cells on glucose plates appear to be in a "quiescent" state that can be prevented by various combinations of lysine, methionine, and tyrosine. Moreover, the quiescent state is characteristic of ~80% of E. coli phylogenetic group B2 multilocus sequence type 73 strains, as well as 22.5% of randomly selected UPEC strains isolated from community-acquired urinary tract infections in Denmark. In addition, E. coli CFT073 quiescence is not limited to glucose but occurs on agar plates containing a number of other sugars and acetate as sole carbon sources. It is also shown that a number of E. coli CFT073 mini-Tn5 metabolic mutants (gnd, gdhA, pykF, sdhA, and zwf) are nonquiescent on glucose M9 minimal agar plates and that quiescence requires a complete oxidative tricarboxylic acid (TCA) cycle. In addition, evidence is presented that, although E. coli CFT073 quiescence and persistence in the presence of ampicillin are alike in that both require a complete oxidative TCA cycle and each can be prevented by amino acids, E. coli CFT073 quiescence occurs in the presence or absence of a functional rpoS gene, whereas maximal persistence requires a nonfunctional rpoS. Our results suggest that interventions targeting specific central metabolic pathways may mitigate UPEC infections by interfering with quiescence and persistence. IMPORTANCE Recurrent urinary tract infections (UTIs) affect 10 to 40% of women. In up to 77% of those cases, the recurrent infections are caused by the same uropathogenic E. coli (UPEC) strain that caused the initial infection. Upon infection of urothelial transitional cells in the bladder, UPEC appear to enter a nongrowing quiescent intracellular state that is thought to serve as a reservoir responsible for recurrent UTIs. Here, we report that many UPEC strains enter a quiescent state when ?10(6) CFU are seeded on glucose M9 minimal medium agar plates and show that mutations in several genes involved in central carbon metabolism prevent quiescence, as well as persistence, possibly identifying metabolic pathways involved in UPEC quiescence and persistence in vivo.

Dataset Information

Variation of intragenic tandem repeat tract of tolA modulates Escherichia coli stress tolerance.

Publications

Variation of intragenic tandem repeat tract of tolA modulates Escherichia coli stress tolerance.

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