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Significance of four methionine sulfoxide reductases in Staphylococcus aureus.

Singh VK, Vaish M, Johansson TR, Baum KR, Ring RP, Singh S, Shukla SK, Moskovitz J - PLoS ONE (2015)

Bottom Line: Cell wall-active antibiotics cause elevated synthesis of methionine sulfoxide reductases (Msrs: MsrA1 and MsrB) in S. aureus.MsrA and MsrB enzymes reduce S-epimers and R-epimers of methionine sulfoxide, respectively, that are generated under oxidative stress.Overall, the data suggests that MsrA1 may be an important virulence factor and MsrB probably plays a balancing act to counter the effect of MsrA1 in S. aureus.

View Article: PubMed Central - PubMed

Affiliation: Department of Microbiology and Immunology, A.T. Still University of Health Sciences, Kirksville, Missouri, United States of America.

ABSTRACT
Staphylococcus aureus is a major human pathogen and emergence of antibiotic resistance in clinical staphylococcal isolates raises concerns about our ability to control these infections. Cell wall-active antibiotics cause elevated synthesis of methionine sulfoxide reductases (Msrs: MsrA1 and MsrB) in S. aureus. MsrA and MsrB enzymes reduce S-epimers and R-epimers of methionine sulfoxide, respectively, that are generated under oxidative stress. In the S. aureus chromosome, there are three msrA genes (msrA1, msrA2 and msrA3) and one msrB gene. To understand the precise physiological roles of Msr proteins in S. aureus, mutations in msrA1, msrA2 and msrA3 and msrB genes were created by site-directed mutagenesis. These mutants were combined to create a triple msrA (msrA1, msrA2 and msrA3) and a quadruple msrAB (msrA1, msrA2, msrA3, msrB) mutant. These mutants were used to determine the roles of Msr proteins in staphylococcal growth, antibiotic resistance, adherence to human lung epithelial cells, pigment production, and survival in mice relative to the wild-type strains. MsrA1-deficient strains were sensitive to oxidative stress conditions, less pigmented and less adherent to human lung epithelial cells, and showed reduced survival in mouse tissues. In contrast, MsrB-deficient strains were resistant to oxidants and were highly pigmented. Lack of MsrA2 and MsrA3 caused no apparent growth defect in S. aureus. In complementation experiments with the triple and quadruple mutants, it was MsrA1 and not MsrB that was determined to be critical for adherence and phagocytic resistance of S. aureus. Overall, the data suggests that MsrA1 may be an important virulence factor and MsrB probably plays a balancing act to counter the effect of MsrA1 in S. aureus.

No MeSH data available.


Related in: MedlinePlus

Adherence of the wild-type S. aureus strain SH1000 and its derivative msr mutant cells to A549 human lung epithelial cells.A total of 5X105 bacterial cells were used in these assays. The left light bar in each panel represents the ratios of the msr mutant relative to wild-type SH1000 in the mixture used to infect the A549 cells. The right dark bar in each panel represents the ratios of the msr mutant in the mixture that adhered to the A549 cells after 1 h of incubation. Values indicate the average of three independent experiments ± standard deviation (* significant at p≤.05).
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pone.0117594.g006: Adherence of the wild-type S. aureus strain SH1000 and its derivative msr mutant cells to A549 human lung epithelial cells.A total of 5X105 bacterial cells were used in these assays. The left light bar in each panel represents the ratios of the msr mutant relative to wild-type SH1000 in the mixture used to infect the A549 cells. The right dark bar in each panel represents the ratios of the msr mutant in the mixture that adhered to the A549 cells after 1 h of incubation. Values indicate the average of three independent experiments ± standard deviation (* significant at p≤.05).

Mentions: The mixture that was used in adherence assays was biased for an msr mutant (~60%) relative to the wild-type S. aureus SH1000 (~40%). In experiments investigating the adherence of this mixture to A549 cells, the MsrA1-deficient mutants (msrA1, msrA and msrAB) showed significantly reduced adherence (Fig. 6). Deficiency of MsrA2, MsrA3, or MsrB did not impact the adherence of the S. aureus cells to A549 cells (Fig. 6).


Significance of four methionine sulfoxide reductases in Staphylococcus aureus.

Singh VK, Vaish M, Johansson TR, Baum KR, Ring RP, Singh S, Shukla SK, Moskovitz J - PLoS ONE (2015)

Adherence of the wild-type S. aureus strain SH1000 and its derivative msr mutant cells to A549 human lung epithelial cells.A total of 5X105 bacterial cells were used in these assays. The left light bar in each panel represents the ratios of the msr mutant relative to wild-type SH1000 in the mixture used to infect the A549 cells. The right dark bar in each panel represents the ratios of the msr mutant in the mixture that adhered to the A549 cells after 1 h of incubation. Values indicate the average of three independent experiments ± standard deviation (* significant at p≤.05).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4334518&req=5

pone.0117594.g006: Adherence of the wild-type S. aureus strain SH1000 and its derivative msr mutant cells to A549 human lung epithelial cells.A total of 5X105 bacterial cells were used in these assays. The left light bar in each panel represents the ratios of the msr mutant relative to wild-type SH1000 in the mixture used to infect the A549 cells. The right dark bar in each panel represents the ratios of the msr mutant in the mixture that adhered to the A549 cells after 1 h of incubation. Values indicate the average of three independent experiments ± standard deviation (* significant at p≤.05).
Mentions: The mixture that was used in adherence assays was biased for an msr mutant (~60%) relative to the wild-type S. aureus SH1000 (~40%). In experiments investigating the adherence of this mixture to A549 cells, the MsrA1-deficient mutants (msrA1, msrA and msrAB) showed significantly reduced adherence (Fig. 6). Deficiency of MsrA2, MsrA3, or MsrB did not impact the adherence of the S. aureus cells to A549 cells (Fig. 6).

Bottom Line: Cell wall-active antibiotics cause elevated synthesis of methionine sulfoxide reductases (Msrs: MsrA1 and MsrB) in S. aureus.MsrA and MsrB enzymes reduce S-epimers and R-epimers of methionine sulfoxide, respectively, that are generated under oxidative stress.Overall, the data suggests that MsrA1 may be an important virulence factor and MsrB probably plays a balancing act to counter the effect of MsrA1 in S. aureus.

View Article: PubMed Central - PubMed

Affiliation: Department of Microbiology and Immunology, A.T. Still University of Health Sciences, Kirksville, Missouri, United States of America.

ABSTRACT
Staphylococcus aureus is a major human pathogen and emergence of antibiotic resistance in clinical staphylococcal isolates raises concerns about our ability to control these infections. Cell wall-active antibiotics cause elevated synthesis of methionine sulfoxide reductases (Msrs: MsrA1 and MsrB) in S. aureus. MsrA and MsrB enzymes reduce S-epimers and R-epimers of methionine sulfoxide, respectively, that are generated under oxidative stress. In the S. aureus chromosome, there are three msrA genes (msrA1, msrA2 and msrA3) and one msrB gene. To understand the precise physiological roles of Msr proteins in S. aureus, mutations in msrA1, msrA2 and msrA3 and msrB genes were created by site-directed mutagenesis. These mutants were combined to create a triple msrA (msrA1, msrA2 and msrA3) and a quadruple msrAB (msrA1, msrA2, msrA3, msrB) mutant. These mutants were used to determine the roles of Msr proteins in staphylococcal growth, antibiotic resistance, adherence to human lung epithelial cells, pigment production, and survival in mice relative to the wild-type strains. MsrA1-deficient strains were sensitive to oxidative stress conditions, less pigmented and less adherent to human lung epithelial cells, and showed reduced survival in mouse tissues. In contrast, MsrB-deficient strains were resistant to oxidants and were highly pigmented. Lack of MsrA2 and MsrA3 caused no apparent growth defect in S. aureus. In complementation experiments with the triple and quadruple mutants, it was MsrA1 and not MsrB that was determined to be critical for adherence and phagocytic resistance of S. aureus. Overall, the data suggests that MsrA1 may be an important virulence factor and MsrB probably plays a balancing act to counter the effect of MsrA1 in S. aureus.

No MeSH data available.


Related in: MedlinePlus