Abstract
BackgroundAll aerobically grown living cells are exposed to oxidative damage by reactive oxygen species (ROS). A major damage by ROS to proteins is caused by covalent modifications of methionine residues giving methionine sulfoxide (Met-SO). Methionine sulfoxide reductases are enzymes able to regenerate methionine and restore protein function after oxidative damage.ResultsWe characterized the methionine sulfoxide reductase genes msrA and msrB in Bacillus subtilis, forming an operon transcribed from a single sigma A-dependent promoter. The msrAB operon was specifically induced by oxidative stress caused by paraquat (PQ) but not by H2O2. Spx, a global oxidative stress regulator in B. subtilis, is primarily responsible for this PQ-specific induction of msrAB expression. In support of this finding, an spx deletion mutant is extremely sensitive to PQ, and increased expression of msrA was identified in a clpX mutant in which Spx accumulated. However, the Spx effect was also visible under conditions where the protein did not accumulate (PQ treatment), suggesting a specific molecular effect at the level of the Spx protein. Indeed, the CXXC motif of Spx was found essential for its function in the PQ-specific induction of msrAB expression. PQ caused a modification of Spx requiring at least one of the cysteines of the CXXC motif of Spx. The PQ modified form of Spx showed a dynamic change in vivo.ConclusionThe Spx mediated PQ-specific regulation pathway of the msrAB operon in B. subtilis is reported. Our results suggest that PQ induced the expression of msrAB partially through an oxidation on Spx via modification of its CXXC motif.
Highlights
All aerobically grown living cells are exposed to oxidative damage by reactive oxygen species (ROS)
The global thiol stress response regulator Spx participates in PQ-specific induction of the msrAB operon To identify regulators that may be responsible for the PQinduced enhancement of msrAB expression, we studied the possible involvement of some previously reported oxidative stress response regulators in B. subtilis
We demonstrated that the expression of the msrAB operon in B. subtilis was significantly induced under PQmediated oxidative stress conditions (Fig. 2)
Summary
All aerobically grown living cells are exposed to oxidative damage by reactive oxygen species (ROS). A major damage by ROS to proteins is caused by covalent modifications of methionine residues giving methionine sulfoxide (Met-SO). Methionine sulfoxide reductases are enzymes able to regenerate methionine and restore protein function after oxidative damage. Among the 20 protein-building amino acids, methionine has a special status. Methionine is highly sensitive to reactive oxygen species (ROS) that modify it covalently, yielding methionine sulfoxide in (page number not for citation purposes). BMC Microbiology 2008, 8:128 http://www.biomedcentral.com/1471-2180/8/128 two enantiomeric forms: R- and S- This reaction is reversible and two non-homologous methionine sulfoxide reductases MsrA and MsrB can restore intact methionines from the S- and R- forms, respectively (reviewed in [8]). A series of thorough analyses have been performed in Enterobacteria (Escherichia coli [9] and Erwinia chrysanthemi [10]), but our knowledge is still scarce in Gram-positive organisms, despite the obvious importance of ROS in pathogenicity [11]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
