catalytic core domain of RNA-dependent RNA polymerase (RdRp) in the family Botourmiaviridae of positive-sense single-stranded RNA [(+)ssRNA] viruses
This group contains the catalytic core domain of RdRp of RNA viruses belonging to the family Botourmiaviridae, order Ourlivirales. The family includes six genera: Ourmiavirus, Botoulivirus, Magoulivirus, Penoulivirus, Rhizoulivirus and Scleroulivirus. Family Botourmiaviridae genomes can be monopartite (Botoulivirus, Magoulivirus, Penoulivirus, Rhizoulivirus and Scleroulivirus) (2-3 kb) or tripartate (Ourmiavirus). Members of genus Ourmiavirus infect plants and the other genera infect fungi. Members of the genera Botoulivirus, Magoulivirus and Scleroulivirus infect fungi from the genera Botrytis, Magnaporthe or Sclerotinia, respectively. Members of the genus Ourmiavirus infect plants: Ourmia melon virus infects melon, producing chlorotic spots and irregular ringspots, Epirus cherry virus produces rasp-leaf symptoms in cherry, and cassava virus C induces severe stunting and a yellow mosaic pattern in cassava. Ourmiavirus replication is dependent on the virus RdRp. Synthesis of the ourmiavirus coat protein from actively replicating RNA3 is necessary for both virion assembly and systemic infection of the host. The ourmiavirus movement protein determines symptoms and forms tubular structures involved in cell-to-cell movement and may undergo post-translational modification. Botoulivirus, magoulivirus and scleroulivirus replication is strictly dependent on the virus RNA-dependent RNA polymerase. 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.",