RNA-dependent RNA polymerase (RdRp) in the genus Aureusvirus of positive-sense single-stranded RNA [(+)ssRNA] viruses, within the Procedovirinae subfamily
This group contains the RdRp of RNA viruses belonging to the Aureusvirus genus within the subfamily Procedovirinae, family Tombusviridae, order Tolivirales. In the Aureusvirus genus plants serve as natural hosts. There are six species in this genus: Cucumber leaf spot virus (CLSV), Elderberry aureusvirus 1, Johnsongrass chlorotic stripe mosaic virus (JCSMV), Maize white line mosaic virus (MWLMV), Pothos latent virus (PoLV), and Yam spherical virus (YSV). Aureusviruses infect various natural host plants but their individual range is generally restricted to a few species, pothos and pigeon pea or lisianthus for PoLV, yam for YSV, sesame for SNMV, cucumber, melon or squash for CLSV and various Poaceae species, mainly maize (MWLMV) or johnsongrass (JCSMV). Aureusviruses are transmitted mechanically and by seeds. Transmission through the soil or by the water circulating in hydroponic systems for PoLV, CLSV and MWLMV, or by the fungus Olpidium bornovanus (for CLSV) have also been reported. 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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