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Multiple methionine sulfoxide reductase genes in Staphylococcus aureus: expression of activity and roles in tolerance of oxidative stress
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| Zeitschriftentitel: | Microbiology |
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| Personen und Körperschaften: | , |
| In: | Microbiology, 149, 2003, 10, S. 2739-2747 |
| Format: | E-Article |
| Sprache: | Englisch |
| veröffentlicht: |
Microbiology Society
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| Schlagwörter: |
| Zusammenfassung: | <jats:p> <jats:italic>Staphylococcus aureus</jats:italic> contains three genes encoding MsrA-specific methionine sulfoxide reductase (Msr) activity (<jats:italic>msrA1</jats:italic>, <jats:italic>msrA2</jats:italic> and <jats:italic>msrA3</jats:italic>) and an additional gene that encodes MsrB-specific Msr activity. Data presented here suggest that MsrA1 is the major contributor of the MsrA activity in <jats:italic>S</jats:italic>. <jats:italic>aureus</jats:italic>. In mutational analysis, while the total Msr activity in <jats:italic>msrA2</jats:italic> mutant was comparable to that of the parent, Msr activity was significantly up-regulated in the <jats:italic>msrA1</jats:italic> or <jats:italic>msrA1</jats:italic> <jats:italic>msrA2</jats:italic> double mutant. Assessment of substrate specificity together with increased reactivity of the cell-free protein extracts of the <jats:italic>msrA1</jats:italic> mutants to anti-MsrB polyclonal antibodies in Western analysis provided evidence that increased Msr activity was due to elevated synthesis of MsrB in the MsrA1 mutants. Previously, it was reported that oxacillin treatment of <jats:italic>S</jats:italic>. <jats:italic>aureus</jats:italic> cells led to induced synthesis of MsrA1 and a mutation in <jats:italic>msrA1</jats:italic> increased the susceptibility of the organism to H<jats:sub>2</jats:sub>O<jats:sub>2</jats:sub>. A mutation in the <jats:italic>msrA2</jats:italic> gene, however, was not significant for the bacterial oxidative stress response. In complementation assays, while the <jats:italic>msrA2</jats:italic> gene was unable to complement the <jats:italic>msrA1</jats:italic> <jats:italic>msrA2</jats:italic> double mutant for H<jats:sub>2</jats:sub>O<jats:sub>2</jats:sub> resistance, the same gene restored H<jats:sub>2</jats:sub>O<jats:sub>2</jats:sub> tolerance in the double mutant when placed under the control of the <jats:italic>msrA1</jats:italic> promoter. However, <jats:italic>msrA1</jats:italic> which was able to complement the oxidative stress response in <jats:italic>msrA1</jats:italic> mutants could not restore the tolerance of the <jats:italic>msrA1</jats:italic> <jats:italic>msrA2</jats:italic> mutants to H<jats:sub>2</jats:sub>O<jats:sub>2</jats:sub> when placed under the control of the <jats:italic>msrA2</jats:italic> promoter. Additionally, although the oxacillin minimum inhibitory concentration of the <jats:italic>msrA1</jats:italic> mutant was comparable to that of the wild-type parent, in shaking liquid culture, the <jats:italic>msrA1</jats:italic> mutant responded more efficiently to sublethal doses of oxacillin. The data suggest complex regulation of Msr proteins and a more significant physiological role for <jats:italic>msrA1</jats:italic>/<jats:italic>msrB</jats:italic> in <jats:italic>S</jats:italic>. <jats:italic>aureus</jats:italic>.</jats:p> |
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| Umfang: | 2739-2747 |
| ISSN: |
1350-0872
1465-2080 |
| DOI: | 10.1099/mic.0.26442-0 |