title: Similarity in gene organization and homology between proteins of animal picornaviruses and a plant comovirus suggest common ancestry of these virus families.
abstract: The amino acid sequences deduced from the nucleic acid sequences of several animal picornaviruses and cowpea mosaic virus (CPMV), a plant virus, were compared. Good homology was found between CPMV and the picornaviruses in the region of the picornavirus 2C (P2-X protein), VPg, 3C pro (proteinase) and 3D pol (RNA polymerase) regions. The CPMV B genome was found to have a similar gene organization to the picornaviruses. A comparison of the 3C pro (proteinase) regions of all of the available picornavirus sequences and CPMV allowed us to identify residues that are completely conserved; of these only two residues, Cys-147 and His-161 (poliovirus proteinase) could be the reactive residues of the active site of a proteinase with analogous mechanism to a known proteinase. We conclude that the proteinases encoded by these viruses are probably cysteine proteinases, mechanistically related, but not homologous to papain.
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D005075:Biological Evolution; D012321:DNA-Directed RNA Polymerases / Q000235:genetics; D005796:Genes; D005814:Genes, Viral; D009029:Mosaic Viruses / Q000235:genetics*; D010447:Peptide Hydrolases / Q000235:genetics; D010849:Picornaviridae / Q000235:genetics*; D013045:Species Specificity; D014764:Viral Proteins / Q000235:genetics*
chemical_list: D014764:Viral Proteins; D012321:DNA-Directed RNA Polymerases; D010447:Peptide Hydrolases