Bacterial DNA-directed RNA polymerase beta subunit (RNA polymerase β subunit or RNAP β)

The **bacterial DNA-directed RNA polymerase beta subunit** is an essential component of the prokaryotic core RNA polymerase enzyme, encoded by the *rpoB* gene[1][3]. This beta subunit (~150 kDa, 1,342 residues in *E. coli*) forms part of the enzyme’s active site, working in concert with the beta-prime (β′), alpha, and omega subunits to synthesize RNA from a DNA template during transcription[1]. The beta and beta-prime subunits together create a crab-claw structure that forms a channel for nucleic acid substrates. RNAP β is vital for bacterial survival, as it catalyzes all cellular RNA synthesis. It is a proven and clinically validated therapeutic target for antibacterials, particularly rifamycins, which inhibit RNA synthesis by binding to the beta subunit and blocking transcript elongation, leading to cell death[2][4]. The beta subunit is also implicated in antimicrobial resistance; mutations in *rpoB* confer resistance to rifamycins, especially in *Mycobacterium tuberculosis*. Its essential role, conservation across bacterial species, and divergence from human RNA polymerases underlie its value as a selective antibacterial drug target[2][4][7][8].

Other names

RNAP β subunitrpoB gene productBeta subunit of DNA-directed RNA polymeraseBeta subunit of RNAP

Inhibition of transcription initiation or elongation by binding the beta subunit and blocking RNA chain extension (for rifamycins)[4]. Binding the "switch region" or other functional motifs of the beta subunit to prevent conformational changes needed for RNA synthesis (for myxopyronin and related drugs)[4]. Prevention of the enzyme’s interaction with promoter DNA or nucleic acid substrates.