title: 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 ΔtolA 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 ΔtolA 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).
authors.affiliation: Laboratory of Food Microbiology and Leuven Food Science and Nutrition Research Centre (LFoRCe), Department of Microbial and Molecular Systems (MS), Faculty of Bioscience Engineering, KU Leuven, Leuven, Belgium.
authors.forename: Kai
authors.initials: K
authors.lastname: Zhou
authors.forename: Chris W
authors.initials: CW
authors.lastname: Michiels
authors.forename: Abram
authors.initials: A
authors.lastname: Aertsen
mesh_terms: D003090:Coliphages / Q000502:physiology; D056915:DNA Copy Number Variations; D004265:DNA Helicases / Q000172:deficiency / Q000235:genetics; D003840:Deoxycholic Acid / Q000494:pharmacology; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism / Q000821:virology; D029968:Escherichia coli Proteins / Q000235:genetics* / Q000378:metabolism; D014644:Genetic Variation; D009994:Osmolar Concentration; D011938:Rec A Recombinases / Q000235:genetics / Q000378:metabolism; D012967:Sodium Dodecyl Sulfate / Q000494:pharmacology; D013312:Stress, Physiological / Q000235:genetics*; D020080:Tandem Repeat Sequences
chemical_list: D029968:Escherichia coli Proteins; C062093:tolA protein, E coli; D003840:Deoxycholic Acid; D012967:Sodium Dodecyl Sulfate; D011938:Rec A Recombinases; C506746:UvrD protein, E coli; D004265:DNA Helicases