catalytic core domain of RNA-dependent RNA polymerase (RdRp) in the family Tymoviridae of positive-sense single-stranded RNA [(+)ssRNA] viruses, in the order Tymovirales
This group contains the catalytic core domain of RdRp of RNA viruses belonging to the family Tymoviridae, order Tymovirales. Virions of the family Tymoviridae are isometric, non-enveloped, about 30 nm in diameter, and contain a single molecule of (+)ssRNA constituting 25#35% of the particle weight. There are 42 species in this family, assigned to three genera (Maculavirus, Marafivirus, and Tymovirus), with two species unassigned to a genus. Members of the Tymovirales order are mainly plant pathogens that are characterized by similarities in their replication-associated polyproteins, which account for the majority of their genomic coding capacity. They are considered to form a group, phylogenetically, referred to as flexiviruses, with filamentous virions. 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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