RNA polymerase enzyme (RNAP or RNA Pol)

RNA polymerase enzyme is a multi-subunit enzyme complex responsible for synthesizing RNA from a DNA template, a process called transcription[1][2][4][5][6][7]. Found in all living organisms and many viruses, it is essential for the first step in gene expression. In bacteria, a single RNA polymerase synthesizes all types of RNA, whereas in eukaryotes, multiple specialized forms exist: RNA polymerase I (rRNA synthesis), II (mRNA and some non-coding RNAs), and III (tRNA and small RNAs)[2][5][6]. The core enzyme typically consists of five subunits (α2, β, β′, ω) and, in bacteria, associates with a sixth, the sigma (σ) factor, to form the holoenzyme for initiation specificity[1][2][4][6]. RNA polymerase is a validated therapeutic target for antibiotics (e.g., rifampicin), and its dysfunction or inhibition underlies the mechanisms of some anticancer agents and toxins[5]. Specificity and essentiality make it a key molecular target for both research and therapy, while resistance or off-target effects remain significant concerns[5].

Other names

DNA-directed RNA polymeraseRNAPRNA PolRNA polymerase IRNA polymerase IIRNA polymerase III (for eukaryotic subtypes)DNA-dependent RNA polymerase

Inhibition of RNA chain initiation by blocking RNAP binding (e.g., rifampicin) - Inhibition of RNA chain elongation (e.g., α-amanitin) - Blocking active site or DNA binding (e.g., actinomycin D)