Expression of Four Methionine Sulfoxide Reductases in Staphylococcus aureus

Abstract EN

Staphylococcus aureus possesses three MsrA enzymes (MsrA1, MsrA2, MsrA3) that reduce the S-epimer of methionine sulfoxide (MetO) and an MsrB enzyme that reduces R-MetO.

The four msr genes are expressed from three different promoters.

The msrA1/msrB genes are coexpressed.

To determine the expression pattern of msr genes, three independent reporter strains were constructed where msr promoter was cloned in front of a promoterless lacZ and the resulting construct was integrated in the chromosome.

Using these strains, it was determined that the msrA1/B expression is significantly higher in S.

aureus compared to msrA2 or msrA3.

Expression of msrA1/B was highest during stationary phase growth, but the expression of msrA2 and msrA3 was highest during the early to midexponential growth phase.

Expression of msrA1/B was induced by oxacillin and the expression of msrA3 was upregulated by salt.

Expression of msrA2 remained unchanged under all tested conditions.