RNA-dependent RNA polymerase (RdRp) in the genus Betacarmovirus of positive-sense single-stranded RNA [(+)ssRNA] viruses, within the Procedovirinae subfamily
This group contains the RdRp of RNA viruses belonging to the Betacarmovirus genus within the subfamily Procedovirinae, family Tombusviridae, order Tolivirales. The single genus Carmovirus was split in 2015 into three genera, each retaining -carmovirus as part of their name: Alphacarmovirus, Betacarmovirus, and Gammacarmovirus. Different carmoviruses infect a wide range of both monocotyledonous and dicotyledonous plants. Viruses tend to remain localized, forming necrosis in artificially infected hosts. There are 4 species in the genus Betacarmovirus: Cardamine chlorotic fleck virus, Hibiscus chlorotic ringspot virus, Japanese iris necrotic ring virus, and Turnip crinkle virus. 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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