catalytic core domain of RNA-dependent RNA polymerase (RdRP) in the Tobaniviridae family of positive-sense single-stranded RNA [(+)ssRNA] viruses
This group contains the catalytic core domain of RdRp of RNA viruses belonging to the family Tobaniviridae, order Nidovirales. Tobaniviridae RNA viruses infect vertebrates; their host organisms include mammals, fish, and snakes. Member viruses have a viral envelope and (+)ssRNA genome. The genome size of Tobaniviruses ranges from 20 to 32 kilobases. The family is the only member of the suborder Tornidovirineae. The family Tobaniviridae has four subfamilies (Piscanivirinae, Remotovirinae, Remotovirinae, and Torovirinae) and eight genera (Bafinivirus, Oncotshavirus, Bostovirus, Infratovirus, Pregotovirus, Sectovirus, Tiruvirus, and Torovirus). The Tobaniviridae family belongs to the order Nidovirales, which currently comprises 88 formally recognized virus species of (+)ssRNA viruses, which are classified into nine virus families across seven different suborders. The structure of Tobaniviridae RdRp contains a RdRp domain as well as a large N-terminal extension that adopts a nidovirus RdRp-associated nucleotidyltransferase (NiRAN) architecture. 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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