Bacterial RNA polymerase switch region (RNAP switch region)

The bacterial RNA polymerase (RNAP) switch region is a vital regulatory hinge located at the base of the enzyme's clamp module. This region mediates the conformational changes—specifically the opening and closing of the clamp—that are required to permit DNA entry into the active site and to stabilize the transcription complex (Mukhopadhyay et al., 2008, Cell). As a target for antimicrobial therapy, the switch region is highly valued because it is essential for bacterial viability and is structurally distinct from the corresponding regions in human RNA polymerases, ensuring high selectivity (Belogurov et al., 2009, Nature). Small molecule inhibitors such as myxopyronin and corallopyronin bind to this site, effectively jamming the hinge and preventing the enzyme from initiating the transcription process (Srivastava et al., 2011, Curr Opin Microbiol). This mechanism of action is distinct from that of rifamycins, which bind to the RNA exit channel, making switch region inhibitors effective against many rifampin-resistant strains. Consequently, this target is a focal point for the development of next-generation antibiotics aimed at treating multidrug-resistant bacterial infections.

Other names

Switch region of bacterial RNA polymeraseRNAP switch regionRNAP clamp switchMyxopyronin binding siteSwitch 1 and Switch 2 regions of RNAP

Inhibition of transcription initiation by binding to the switch region and preventing the conformational changes (opening/closing) of the RNAP clamp required for DNA binding.