Bacterial DNA-directed RNA polymerase subunit beta' switch region (RNAP β′ switch region)

The bacterial DNA-directed RNA polymerase (RNAP) subunit beta' switch region is a critical structural hinge located at the base of the RNAP clamp, which facilitates the conformational changes necessary for DNA binding and transcription initiation (Mukhopadhyay et al., 2008, Cell). This region acts as a 'switch' that allows the enzyme to transition between an open state, which permits DNA entry into the active-site cleft, and a closed state, which secures the DNA for processive RNA synthesis (Belogurov et al., 2009, Nature). Because this region is highly conserved across diverse bacterial species and is essential for viability, it serves as a potent target for a class of antibiotics known as switch-region inhibitors (SRIs) (Srivastava et al., 2011, Curr Opin Microbiol). Drugs such as myxopyronin, corallopyronin, and fidaxomicin bind specifically to this pocket, preventing the necessary movement of the clamp and effectively halting the transcription process (Ebright, 2011, RNA Biol). This mechanism is distinct from that of rifamycins, which bind to the RNAP active-site channel, meaning that switch-region inhibitors remain effective against many rifampin-resistant bacterial strains, including Mycobacterium tuberculosis (Maffioli et al., 2017, Cell). Consequently, the beta' switch region is a focal point for the development of novel broad-spectrum antibacterial agents aimed at overcoming multi-drug resistance.

Other names

RNA polymerase switch regionRNAP switch regionBeta' subunit switch regionSwitch-region of bacterial RNA polymeraseRNAP switch-2 region

Inhibition of the conformational 'switch' movement required for the RNA polymerase clamp to close around DNA, thereby preventing the formation of a stable transcription initiation complex (Switch-region inhibition).