catalytic core domain of RNA-dependent RNA polymerase (RdRp) in the genus Crohivirus 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 Crohivirus genus within the family Picornaviridae, order Picornavirales. The Crohivirus contains viruses with (+)ssRNA genomes that produce nonenveloped virions. Crohivirus is a new genus containing two species, Crohivirus A and Crohivirus B. Crohivirus A (Crohivirus 1, CroV-1) is a novel picornavirus found the lesser red musk shrew (Crocidura hirta) which is found in southern Africa. The genome sequence is most closely related to the parechoviruses. Crohivirus B consists of a virus which has been found in the straw-colored fruit bat (Eidolon helvum). 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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