catalytic core domain of RNA-dependent RNA polymerase (RdRp) in the family Iflaviridae of positive-sense single-stranded RNA [(+)ssRNA] viruses, in the order Picornavirales
This group contains the catalytic core domain of RdRp of RNA viruses belonging to the family Iflaviridae, order Picornavirales. Iflaviridae is a family of small non-enveloped viruses with (+)ssRNA genomes of approximately 9-11 kilobases in length encoding a single polyprotein. All members infect arthropod hosts with the majority infecting insects. Beneficial and pest insects serve as hosts and infections can be symptomless (Nilaparvata lugens honeydew virus 1), cause developmental abnormalities (deformed wing virus, Varroa destructor virus 1, sacbrood virus), behavioral changes (deformed wing virus, Varroa destructor virus 1, slow bee paralysis virus, sacbrood virus) and premature mortality (deformed wing virus, Varroa destructor virus 1, slow bee paralysis virus, infectious flacherie virus, sacbrood virus). 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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