Fig. 8. Model of the regulation cycle for CtsR repression. In non-stressed cells, the active CtsR dimer is positively influenced and stabilized by McsA, thereby repressing transcription of class III heat shock genes. After stress, McsB modifies CtsR, negatively affecting its active conformation, and targets the repressor for degradation by ClpCP. Transcription of class III heat shock genes is induced. The arrow symbolizes positive regulation, the cross symbolizes blocked degradation, an asterisk symbolizes modification, and a dashed line instability.