catalytic core domain of RNA-dependent RNA polymerase (RdRp) in the genus Passerivirus of positive-sense single-stranded RNA [(+)ssRNA] viruses, within the family Picornaviridae
This group contains the catalytic core domain of the RdRp of RNA viruses belonging to the Passerivirus genus within the family Picornaviridae, order Picornavirales. The Passerivirus contains viruses with (+)ssRNA genomes that produce nonenveloped virions. There are two species in this genus: Passerivirus A and a second, novel passerivirus (Passerivirus B) that was discovered in 2018 in a population of Hungarian home-reared finches, where it achieved an over 50 percent mortality rate. Birds serve as natural hosts. RdRps catalyze RNA template-dependent formation of phosphodiester bonds between ribonucleotides in the presence of divalent metal ions. The initiation of synthesis occurs at the 3'-end of the template in a VPg-dependent manner, and proceeds in the direction of 5'-3'. The active sites of RdRps are highly conserved in different species of picornaviruses. 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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