Controls rRNA transcription by binding to the RNA polymerase (RNAP). Required for the stringent response to starvation, oxidative and genotoxic stresses as well as control of rRNA under normal growth conditions. Interacts directly with the N-terminus of the RNA polymerase subunit beta (RpoB). Induced by DNA damage and starvation. Essential for growth, it cannot be disrupted. Belongs to the CarD family.