A D, D‐carboxypeptidase is required for Vibrio cholerae halotolerance. (February 2015)

• Record Type: Journal Article
• Authors: Möll, Andrea; Dörr, Tobias; Alvarez, Laura; Davis, Brigid M.; Cava, Felipe; Waldor, Matthew K.
• Is Part Of: Environmental microbiology. Volume 17:Number 2(2015:Feb.)
• Page Start: 527
• Page End: 540
• Publication Date: 2015-02
• Subjects: Microbial ecology -- Periodicals; Environmental Microbiology -- Periodicals; 579.17
• DOI: 10.1111/1462-2920.12779
• Languages: English
• ISSNs: 1462-2912

Abstract

<abstract abstract-type="main"> <title>Summary</title> <p>The biological roles of low molecular weight penicillin‐binding proteins (LMW PBP) have been difficult to discern in Gram‐negative organisms. In <italic>E</italic><italic>scherichia coli</italic>, mutants lacking these proteins often have no phenotype, and cells lacking all seven LMW PBPs remain viable. In contrast, we report here that <italic>V</italic><italic>ibrio cholerae</italic> lacking DacA‐1, a PBP5 homologue, displays slow growth, aberrant morphology and altered peptidoglycan (PG) homeostasis in Luria–Bertani (LB) medium, as well as a profound plating defect. DacA‐1 alone among <italic>V</italic><italic>. cholerae's</italic> LMW PBPs is critical for bacterial growth; mutants lacking the related protein DacA‐2 and/or homologues of PBP4 or PBP7 displayed normal growth and morphology. Remarkably, the growth and morphology of the <italic>dac</italic><italic>A</italic><italic>‐1</italic> mutant were unimpaired in LB media containing reduced concentrations of NaCl (100 mM or less), and also within suckling mice, a model host for the study of cholera pathogenesis. Peptidoglycan from the <italic>dac</italic><italic>A</italic><italic>‐1</italic> mutant contained elevated pentapeptide levels in standard and low salt media, and comparative analyses suggest that DacA‐1 is <italic>V</italic><italic>. cholerae's</italic> principal DD‐carboxypeptidase. The basis for the <italic>dac</italic><italic>A</italic><italic>‐1</italic> mutant's halosensitivity is unknown; nonetheless, the mutant's survival in biochemically uncharacterized environments (such as the suckling mouse intestine) can be used as a reporter of low Na<sup>+</sup> content.</p> </abstract>