DNA-directed RNA polymerase beta subunit (prokaryotic) (RNA polymerase β subunit (often abbreviated as RNAP β or rpoB))

The **DNA-directed RNA polymerase beta subunit** is an essential component of the bacterial RNA polymerase enzyme complex, encoded by the rpoB gene[1][7]. Along with the β′, α, and ω subunits, it forms the "core enzyme" that synthesizes RNA from a DNA template during transcription. The β subunit contains structural features critical for nucleotide binding and catalysis, and contributes to the formation of the polymerase's catalytic center. The active site is formed through interactions with the β′ subunit, creating a sophisticated clamp-like quaternary structure (crab claw) that positions DNA and enables processive RNA synthesis. Antibiotics such as rifampicin target this subunit, halting bacterial transcription. Mutations in the beta subunit's rpoB gene are a leading cause of antibiotic resistance in several clinically important bacteria, most notably *Mycobacterium tuberculosis*[1][3][7].

Other names

rpoB (gene name for the subunit in bacteria)RNAP β subunitRNA polymerase betaDNA-dependent RNA polymerase beta subunitBeta subunit of bacterial RNA polymerase

Rifamycins: inhibit the β subunit by preventing RNA chain elongation during transcription[1][3]. Fidaxomicin: binds and inhibits the initiation stage of transcription by interfering with the opening of DNA and RNAP clamp[1]. These drugs block RNA synthesis, leading to bacterial cell death.