Induction of expression by cell-wall targeting antibiotics in .

is one of the major bacteria of the human oral cavity that is associated with dental caries. The pathogenicity of this bacterium is attributed to its ability to rapidly respond and adapt to the ever-changing conditions of the oral cavity. The major player in this adaptive response is ClpP, an intracellular protease involved in degradation of misfolded proteins during stress responses. encodes a single gene with an upstream region uniquely containing multiple tandem repeat sequences (RSs). Here, we explored expression of with respect to various stresses and report some new findings. First, we found that at sub-inhibitory concentration, certain cell-wall damaging antibiotics were able to induce expression. Specifically, third- and fourth-generation cephalosporins that target penicillin-binding protein 3 (PBP3) strongly enhanced the expression. However, induction of was weak when the first-generation cephalosporins with lower affinity to PBP3 were used. Surprisingly, carbapenems, which primarily target PBP2, induced expression of the least. Second, we found that a single RS element was capable of inducing expression as efficiently as with the wild-type seven RS elements. Third, we found that the RS-element-mediated modulation of expression was strain dependent, suggesting that specific host factors might be involved in the transcription. And finally, we observed that ClpP regulates its own expression, as the expression of was higher in a -deficient mutant. This suggests that ClpP is involved in the degradation of activator(s) involved in its own transcription.