catalytic core domain of RNA-dependent RNA polymerase (RdRp) in a novel picorna-like Drosophila virus, Nora virus
This group contains the catalytic core domain of RNA-dependent RNA polymerase (RdRp) in the unclassified Nora virus, a new picorna-like virus family. Nora virus has a (+)ssRNA genome followed by a poly(A) tail. Unlike other picorna-like viruses, the genome has four open reading frames (ORFs). One ORF encodes a picornavirus-like cassette of proteins for virus replication, including an iflavirus-like RdRp and a helicase that is related to those of mammalian picornaviruses. The three other ORFs are not closely related to any previously described viruses. Nora virus is present as a persistent infection in several tested laboratory stocks and wild-caught flies. The RdRp domain displays a right hand with three functional subdomains, called fingers, palm, and thumb. All RdRps contain conserved polymerase motifs (A-G), located in the palm (A-E motifs) and finger (F-G) subdomains. All these motifs have been implicated in RdRp fidelity such as processes of correct incorporation and reorganization of nucleotides.
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