RNA-dependent RNA polymerase

Viral RNA-dependent RNA polymerases (RdRPs) are a class of nucleic acid polymerases bearing unique features from global architecture to catalytic mechanisms. RNA-dependent RNA polymerase involved in post-transcriptional gene silencing (PTGS). Possesses ssRNA and ssDNA-dependent polymerase activity, but does not have priming activity. In recent years, numerous viral RdRP crystal structures have improved the understanding of these molecular machines, in particular, for how they carry out each nucleotide addition cycle (NAC) as directed by the RNA template.