RNA-dependent RNA polymerase (RdRp) in the family Dicistroviridae of positive-sense single-stranded RNA [(+)ssRNA] viruses, in the order Picornavirales
This group contains the RdRp of RNA viruses belonging to the family Dicistroviridae, order Picornavirales. Dicistroviridae is a family of small non-enveloped viruses with a (+)ssRNA genome of approximately 8-10 kilobases. The family contains 3 genera: Aparavirus, Cripavirus, and Triatovirus. All members infect arthropod hosts with some having devastating economic consequences, such as acute bee paralysis virus, Kashmir bee virus, and Israeli acute paralysis virus in domesticated honeybees, and taura syndrome virus and mud crab virus in the seafood industry. On the contrary, host specificity and other desirable traits make several members of this group amenable to development as biopesticides for insect control, such as Solenopsis invicta virus 1 against fire ants, and triatoma virus against triatomine bugs that vector Chagas disease. Members in the family Dicistroviridae have similarity to viruses in the Picornavirales members (Iflaviridae, Picornaviridae, Marnaviridae and Secoviridae). The genomes of viruses of these taxa encode proteins with helicase, 3C-like protease, and RdRp domains, as well as capsid proteins with related structures, although the genome organizations can differ among viruses. 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.
Jiyao W et al.(2023). "The conserved domain database in 2023.",