Role of a short tandem leucine/arginine repeat in strong mutator phenotype acquisition in a clinical isolate of Salmonella Typhimurium

Authors

  • Hervé Le Bars,

    1. Equipe Microbiologie, EA 1254, SFR BIOSIT, Université Européenne de Bretagne, Rennes, France
    2. Pôle Microorganismes, CHU Pontchaillou, Rennes Cedex, France
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  • Latifa Bousarghin,

    1. Equipe Microbiologie, EA 1254, SFR BIOSIT, Université Européenne de Bretagne, Rennes, France
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  • Martine Bonnaure-Mallet,

    1. Equipe Microbiologie, EA 1254, SFR BIOSIT, Université Européenne de Bretagne, Rennes, France
    2. Pôle Microorganismes, CHU Pontchaillou, Rennes Cedex, France
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  • Anne Jolivet-Gougeon

    Corresponding author
    1. Pôle Microorganismes, CHU Pontchaillou, Rennes Cedex, France
    • Equipe Microbiologie, EA 1254, SFR BIOSIT, Université Européenne de Bretagne, Rennes, France
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Correspondence: Anne Jolivet-Gougeon, Equipe Microbiologie, EA 1254, Faculté des Sciences Pharmaceutiques et Biologiques, Université Européenne de Bretagne, Université de Rennes I, 2 Avenue du Professeur Léon Bernard, 35043 Rennes, France. Tel.: (33) 02 23 23 49 05; fax: (33) 02 23 23 49 13; e-mails: anne.gougeon@univ-rennes1.fr; anne.gougeon@chu-rennes.fr

Abstract

In this prospective study, a strong mutator strain of Salmonella Typhimurium was isolated from a collection of 130 human clinical strains of Salmonella. Sequence analysis of the mutS, mutL, and mutH genes, which encode three proteins that are essential for initiation of methyl-directed DNA mismatch repair, revealed insertion of a short tandem repeat (STR) of leucine/alanine in the histidine kinase-like ATPase domain of MutL. The role of this STR in the acquisition of the strong mutator phenotype was confirmed by the construction of an isogenic mutant (6bpinsmutL) from a normomutator strain of Salmonella Heidelberg. This result adds to the sparse body of knowledge about strong mutators and highlights the role of this STR as a hotspot for the acquisition of a strong mutator phenotype in Salmonella.

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