RNA polymerase subunit beta (RNAP β)

The **RNA polymerase subunit beta** (encoded by the **rpoB** gene) is the second largest subunit of the bacterial DNA-dependent RNA polymerase (RNAP) core enzyme. The RNAP core in bacteria comprises five subunits: two alpha (α), one beta (β), one beta prime (β’), and one omega (ω)[2][3][4][5][6][7]. The beta subunit, together with beta prime, forms the catalytic center essential for the synthesis of RNA from a DNA template during transcription[3][7]. This subunit interacts directly with both DNA and nascent RNA and provides key binding sites for transcription inhibitors, making it a major target for antibiotics such as rifampicin and other rifamycins[2][3][4][7]. Mutations in the rpoB gene, which encodes the beta subunit, are known to confer resistance to rifampicin, notably in multiple clinically relevant pathogens such as *Mycobacterium tuberculosis*, making rpoB a critical biomarker for antibiotic resistance screening[3][7]. The beta subunit is unique to bacteria, distinguishing it from eukaryotic polymerase subunits, and is regarded as an enzyme and a crucial drug target for antibacterial therapy[2][3][4][7].

Other names

RNA polymerase β subunitRNAP betaRpoB (gene name)Beta subunit of DNA-dependent RNA polymerase

Inhibition of RNA synthesis by binding to the beta subunit, blocking the path of the elongating RNA, preventing transcription elongation (as for rifamycins)