Reaction related substrates of RNA polymerase

The enzyme requires four ribonucleotide triphosphates (NTP: ATP, GTP, CTP, UTP) as the substrate of RNA polymerase, DNA as the template, and divalent metal ions Mg2+and Mn2+as the necessary cofactor of the enzyme.

The catalytic reaction is expressed as: (NMP) n+NTP → (NMP) n+1+PPi. The synthesis direction of the RNA chain is also 5 '→ 3', with the first nucleotide carrying three phosphate groups. Afterwards, each nucleotide is added to remove a pyrophosphate, forming a phosphodiester bond. The rapid hydrolysis of pyrophosphate energy drives the polymerization reaction. Unlike DNA polymerase, RNA polymerase can directly synthesize RNA chains on the template without primer; RNA polymerase can partially untie the two strands of DNA, so it is unnecessary to completely untie the double strands of DNA during transcription, and RNA polymerase has no proofreading function.