title: Methionine sulfoxide reductase A (MsrA) deficiency affects the survival of Mycobacterium smegmatis within macrophages.
abstract: Methionine sulfoxide reductase A (MsrA) is an antioxidant repair enzyme which reduces oxidized methionine to methionine. Since oxidation of methionine in proteins impairs their function, an absence of MsrA leads to abnormalities in different organisms, including alterations in the adherence patterns and in vivo survival of certain pathogenic bacteria. To understand the role of MsrA in intracellular survival of bacteria, we disrupted the gene encoding MsrA in Mycobacterium smegmatis through homologous recombination. The msrA mutant strain of M. smegmatis exhibited significantly reduced intracellular survival in murine J774A.1 macrophages compared to the survival of its wild-type counterpart. Furthermore, immunofluorescence and immunoblotting of phagosomes containing M. smegmatis strains revealed that the phagosomes with the msrA mutant strain acquired both p67(phox) of phagocyte NADPH oxidase and inducible nitric oxide synthase much earlier than the phagosomes with the wild-type strain. In addition, the msrA mutant strain of M. smegmatis was observed to be more sensitive to hydroperoxides than the wild-type strain was in vitro. These results suggest that MsrA plays an important role in both extracellular and intracellular survival of M. smegmatis.
authors.affiliation: Department of Microbiology and Immunology, University of Texas Health Science Center, San Antonio, Texas 78229, USA.
authors.forename: T
authors.initials: T
authors.lastname: Douglas
authors.forename: D S
authors.initials: DS
authors.lastname: Daniel
authors.forename: B K
authors.initials: BK
authors.lastname: Parida
authors.forename: C
authors.initials: C
authors.lastname: Jagannath
authors.forename: S
authors.initials: S
authors.lastname: Dhandayuthapani
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000502:physiology*; D002460:Cell Line; D005455:Fluorescent Antibody Technique; D005609:Free Radicals; D016680:Genome, Bacterial; D008264:Macrophages / Q000382:microbiology*; D026901:Membrane Transport Proteins / Q000235:genetics / Q000502:physiology*; D051379:Mice; D009154:Mutation; D020102:Mycobacterium smegmatis / Q000502:physiology*; D019001:Nitric Oxide Synthase / Q000032:analysis; D052247:Nitric Oxide Synthase Type II; D018384:Oxidative Stress; D010588:Phagosomes / Q000378:metabolism; D010750:Phosphoproteins / Q000032:analysis
chemical_list: D001426:Bacterial Proteins; D005609:Free Radicals; D026901:Membrane Transport Proteins; D010750:Phosphoproteins; C066202:msrA protein, Staphylococcus epidermidis; C079789:neutrophil cytosol factor 67K; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse