catalytic core domain of RNA-dependent RNA polymerase (RdRp) in the family Astroviridae of positive-sense single-stranded RNA [(+)ssRNA] viruses
This group contains the catalytic core domain of RdRp of RNA viruses belonging to the family Astroviridae, order, Stellavirales. Astrovirus has a non-segmented, (+)ssRNA genome within a non-enveloped icosahedral capsid. The family Astroviridae comprises two genera, Mamastrovirus, which infect mammals, and Avastrovirus, which infect birds. Astroviruses have been isolated from stools from a wide variety of mammals and birds. Human astroviruses have been shown to be an important cause of gastroenteritis in young children. Duck astrovirus causes an often-fatal hepatitis in ducklings. Astroviruses infecting turkeys, guinea fowl and chickens affect multiple organs, including the kidney and thymus. 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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