DNA-dependent RNA polymerase

DNA-dependent RNA polymerase (DdRp) plays a role in transcription. It catalyzes the synthesis of the RNA strand that is complementary to a DNA template. DdRp is an essential protein encoded in the genomes of some cytoplasmic dsDNA viruses. Other viruses make use of the host's DdRp.

Naming: By convention viral polymerases are called RNA/DNA-dependent whereas cellular polymerases are called RNA/DNA-directed.

Enzymatic reaction:

• RNA nucleotidyltransferase (DNA-dependent) EC 2.7.7.6 RHEA:21248

Mechanism DNA-dependent RNA polymerases are characterized by a conserved motif in which two conserved aspartic acid residues are bound to two magnesium ions. The reaction begins with the deprotonation of primer's 3' OH, in a manner that doesn't require a base . Subsequently, the 3'-oxygen acts as a nucleophile to attack the phosphate bond and eventually releases a pyrophosphate.