hrcA
HrcA is a transcriptional repressor protein found in many bacteria that regulates the heat‑shock protein response. It normally binds to a specific DNA sequence called the CIRCE (Controlling Inverted Repeat of Chaperonin Expression) element, which is located upstream of the promoter for genes encoding heat‑shock proteins, such as the chaperonin GroES–GroEL and the ATPase ClpB. When the cell is at normal temperatures, HrcA occupies the CIRCE site and prevents transcription of these heat‑shock genes.
Upon exposure to stressful conditions, such as elevated temperatures or chemical denaturants, HrcA releases from the
The HrcA protein typically contains a helix‑turn‑helix DNA‑binding domain at its N‑terminus and a regulatory domain
Structurally, crystal and cryo‑EM studies have revealed that HrcA can form dimers or tetramers, depending on
Because of its central role in bacterial stress responses, HrcA has been investigated as a potential target