B-254. The Essential Enolase of Staphylococcus aureus Is Involved in Autolysis

Li Zheng, Y. Ji;
Univ. of Minnesota, St. Paul, MN.

The recent emergence of hospital- and community-acquired Methicillin resistant Staphylococcus aureus highlights an urgent need for developing novel and/or alternative antimicrobial agents. Our previous studies indicate that a putative glycoprotein (Gcp) is a unique target for the development of new class antibiotics since Gcp is exported protein and essential for bacterial survival in vitro in culture and in vivo during infection. We also demonstrated that Gcp is necessary for both antibiotic and detergent-induced autolysis. Our proteomic analysis indicates that Gcp affects the expression of a cell-surface protein enolase (eno), which is also required for S. aureus survival. Therefore, we hypothesized that the involvement of Gcp in autolysis may result from its impact on enolase. To test our hypothesis, we created a TetR-regulated enolase antisense isogenic strain using a clinical human S. aureus isolate and examined the influence on bacterial survival and autolysis of the down-regulation of eno expression. We found that the induction of eno antisense RNA expression with an inducer, anhydrotetracycline (ATc), significantly inhibited bacterial growth in a dose-dependent manner. A high dose of the inducer ATc caused a lethal effect, but had no effect on a control strain, indicating the essentiality of enolase in S. aureus. Moreover, we found that the down-regulation of eno expression dramatically decreased autolysis-induced by Triton X-100 and high concentration of NaCl, whereas had slightly influence on Penicillin-induced lysis. The above data suggest that enolase and Gcp are involved in different mechanisms of autolysis in S. aureus. These findings may provide new insights into the biological function of both essential proteins.