catalytic core domain of RNA-dependent RNA polymerase (RdRp) in the genus Rosavirus 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 Rosavirus genus within the family Picornaviridae, order Picornavirales. The Rosavirus contains viruses with (+)ssRNA genomes that produce nonenveloped virions. This genus contains three species Rosavirus A, Rosavirus B and Rosavirus C found in rats. The name rosavirus is derived from rodent stool-associated picornavirus. Viral RNA was detected in fecal samples of humans and rodents [canyon mouse (Peromyscus crinitus), brown rat (Rattus norvegicus), black rat (R. rattus), Sikkim rat (R. andamanensis), chestnut white-bellied rat (Niviventer fulvescens)]. Eight genetic types are distinguished by means of phylogenetic analysis (Rosavirus A: 2 types; Rosavirus B: 2 types; Rosavirus C: 4 types). 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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