InterPro domain: IPR007855

This entry represents various eukaryotic RNA-dependent RNA polymerases (RDRP; 2.7.7.48 ), such as RCRP-1, RDRP-2 and RDRP-6. These enzymes are involved in the amplification of regulatory microRNAs during post-transcriptional gene silencing [ 1 ]; they are also required for transcriptional gene silencing. Double-stranded RNA has been shown to induce gene silencing in diverse eukaryotes and by a variety of pathways [ 2 ]. These enzymes also play a role in the RNA interference (RNAi) pathway, which is important for heterochromatin formation, accurate chromosome segregation, centromere cohesion and telomere function during mitosis and meiosis. RDRP enzymes are highly conserved in most eukaryotes, but are missing in archaea and bacteria. The core catalytic domain of RDRP enzymes is structurally similar to the beta' subunit of DNA-dependent RNA polymerases (DDRP), however the other domains of DDRP show no similarity to those of RDRP.

This entry also includes QDE-1 from the filamentous fungus Neurospora. QDE-1 is both an RdRP and a DNA-dependent RNA polymerase (DdRP). It is able to synthesize RNA from both ssRNA and single-stranded DNA (ssDNA) [ 3 ].

1. Evolutionary connection between the catalytic subunits of DNA-dependent RNA polymerases and eukaryotic RNA-dependent RNA polymerases and the origin of RNA polymerases. BMC Struct. Biol. 3, 1
2. On the origin and functions of RNA-mediated silencing: from protists to man. Curr. Genet. 50, 81-99
3. The DNA/RNA-dependent RNA polymerase QDE-1 generates aberrant RNA and dsRNA for RNAi in a process requiring replication protein A and a DNA helicase. PLoS Biol. 8