Conditional Mutation of an Essential Putative Glycoprotease Eliminates Autolysis in Staphylococcus aureus

Abstract

Our previous studies demonstrated that a putative Staphylococcus aureus glycoprotease (Gcp) is essential for bacterial survival, indicating that Gcp may be a novel target for developing antibacterial agents. However, the biological function of Gcp is unclear. In order to elucidate the reason that Gcp is required for growth, we examined the role of Gcp in bacterial autolysis, which is an important biological process for bacterial growth. Using both a spacp-regulated gcp expression strain and a TetR-regulated gcp antisense expression strain, we found that the down-regulation of gcp expression can effectively inhibit Triton X-100-induced lysis, eliminate penicillin-and vancomycin-caused cell lysis, and dramatically increase tolerance to hydrolases. Moreover, we determined whether resistance to lysis is due to a defect in murein hydrolase activity by using a zymogram analysis. The results showed that the cell lysate of a down-regulated gcp expression mutant displayed several bands of decreased murein hydrolytic activity. Furthermore, we explored the potential mechanism of Gcp's involvement in autolysis and demonstrated that Gcp may function independently from several key autolysins (Atl, LytM, and LytN) and regulators (ArlRS, Mgr/Rat, and CidA). Taken together, the above results indicate that the essential Gcp is involved in the modification of substrates of murein hydrolases as well as in the regulation of expression and/or activity of some murein hydrolases, which, in turn, may play important roles in bacterial viability.

Conserved Network of Proteins Essential for Bacterial Viability

“…Depletion of yjeE and ygjD similarly gave rise to (at least a subset of) very enlarged cells that had defective morphologies, consistent with a link to cell envelope processes. It should be noted that conditional mutation of gcp in Staphylococcus aureus has also been linked to effects on cell wall turnover (74). In each case, the enlarged cells seen during yjeE and ygjD depletion showed a highly unusual pattern of DNA distribution that has only been seen previously when E. coli strains are starved for thymine.…”

The Staphylococcus aureus AirSR Two-Component System Mediates Reactive Oxygen Species Resistance via Transcriptional Regulation of Staphyloxanthin Production

“…To investigate if the airSR TCS transcriptionally regulates the promoter of the crtOPQMN operon, we constructed a crt promoter-lux (luxABCDE) reporter using the pCY1006 vector (44), as previously described (45). The upstream crt promoter region was PCR amplified with primers Pcrt For-lux/Pcrt Rev-lux (listed in Table 2), purified, and digested with EcoRI and SmaI (NEB).…”

Characterization of essential enolase in Staphylococcus aureus

“…Moreover, it has been demonstrated that Clp protease activity affects the expression of regulators, including lytSR, lrgAB, arlRS and rat (Michel et al 2006), which are involved in the modulation of murein hydrolases. Recently, we have demonstrated that a putative glycoprotease (Gcp) modulates the process of S. aureus autolysis (Zheng et al 2007).…”