Beta subunit of bacterial RNA polymerase (None universally used; β is common in scientific literature but not a standardized abbreviation outside structural discussions.)

The beta subunit is one of the two large, catalytically active protein components of the bacterial RNA polymerase core enzyme, vital for the transcription of DNA into RNA. Encoded by the *rpoB* gene, it weighs ~150 kDa and comprises over 1300 amino acids. With the beta-prime subunit, it forms the main catalytic core, which interacts with incoming ribonucleotides and helps coordinate their addition to the nascent RNA strand. The beta subunit contains structural features such as the flap domain (which covers the RNA exit channel and is involved in transcriptional pausing and termination) and forms part of the DNA binding clamp that ensures processive transcription. It is the direct target of rifamycin antibiotics, which inhibit bacterial RNA synthesis—a mechanism widely exploited for the treatment of tuberculosis and other bacterial diseases. Resistance arises predominantly via point mutations in *rpoB*, reducing drug binding affinity[1][5].

Other names

RNAP β subunitRpoBRNA polymerase beta subunitbeta polypeptide of DNA-directed RNA polymerase

Rifamycins bind to the beta subunit and inhibit RNA synthesis by blocking the elongation of the RNA chain. Other inhibitors may target the active site or allosteric sites, interfering with catalysis or complex formation.