Protein
RNA-directed RNA polymerase
Organism
Red clover necrotic mosaic virus
Function
RNA-dependent RNA polymerase, made of isoforms p88 and p27, plays an essential role in the replication of the bipartite viral genome composed of RNA-1 and RNA-2. Replicase proteins p88 and p27 interact together and selectively recruit viral replication templates as well as other essential components into intracellular membranes for the assembly of the 480 kDa viral replicase complex. Mechanistically, isoform protein p27 binds to the Y-shaped RNA element (YRE) located in the 3' UTR of RNA2 via a direct RNA-protein interaction and to RNA1 in a translation-coupled manner. This RNA-binding activity allows RNA2 recruitment to host membranes. The viral replicase complex synthesizes the dsRNA genome from the genomic ssRNA(+). It recognizes internal subgenomic promoters on the negative-sense RNA to transcribe the 3' co-terminal subgenomic RNAs that will generate the capsid and movement proteins. In addition, the viral replication process requires the trigger of an intracellular ROS burst mediated by p27 recruitment of the host ROS-generating machinery. The viral replicase complex also acts as a suppressor of RNA-mediated gene silencing, known as post-transcriptional gene silencing (PTGS), a mechanism of plant viral defense that limits the accumulation of viral RNAs.
Similarity
Belongs to the tombusviridae RNA polymerase family.
Sequence
MGFINLSLFDVDKLMVWVSKFNPGKILSAICNLGIDCWNRFRKWFFGLNFDAHMWAVDAFIPLMPHYTEQMERVVDDFCSETPESKLEDCLELDTSVNEFFDEEVYKKDEEGVMKLQRSAARKHIKRVRPGMMQAAIKAVETRIRNRHTIFGDDMGKVDEAAVRATASDICGEFKINEHHTNALVYAAAYLAMTPDQRSIDSVKLAYNPKSQARRTLVSAIRENKAVAGFKSLEDFLGGPLSFPVEDAPYPILGIPEIRVAEKRASRVMKSKRVVGLPAVSAGLKVCVHQTSLHNMIVSLERRVFRVKNSAGELVVPPKPIQNAFDSISYFREEWLRKLSHKGQILKSSLADVVACYSSEKRKLYQKAADSLEKKPVQWRDSKVQAFIKVEKLECDTKDPVPRTIQPRSKRYNLAIGQYLRLNEKKMLDSIDDVFKEKTVLSGLDNRAQGRAIAHKWRKYQNPIGIGLDASRFDQHCSVDALKFEQTFYKACFPGDQQLETLLKWQLSNTGSALLPTGELVRYRTKGCRMSGDINTGLGNKILMCSMVHAFLKETGVRASLANNGDDCVLFCEKGDYEQINRNLEQWFLCRGFEMTVEKPVDVLEKVAFCRSQPVCIATQWAMVRQLGSLSRDCFSTQDWLNPKTFKDAMNALGQCNGIINDGVPIHMAQAKLMHRIGGNRKFNLDALHKQMEYSWRDRLGKRTNLLWSEVEDATRLSYFRAFGIEPYIQRIVEEYFSQVEITCEGRSTNVLPTHYSRIHKDLIKAR