title: Homologous proteins encoded by yeast mitochondrial introns and by a group of RNA viruses from plants.
abstract: Hensgens et al. (1983a) have demonstrated the existence of distant homology (averaging 19.6%) between the central sections of seven proteins encoded by introns (and one product of an apparently independent gene) in yeast mitochondrial DNA. The homologous regions are typically segments of about 115 amino acids within open reading frames of about 10(3) bases. Genetic studies indicate that at least two of these proteins are required for the splicing of mitochondrial transcripts. This paper reports that two distantly related proteins of Mr 30,000 that are encoded by different strains of tobacco mosaic virus both contain central sections whose amino acid sequences are 15% to 23% identical in a single alignment to those of one group of four intron-encoded proteins, and possess certain groups of conserved residues also characteristic of the mitochondrial proteins. Genetic studies implicate these proteins in the spreading of viral lesions. While this level of identity cannot establish conclusively that the proteins are related, it suggests the possibility of a functional and/or evolutionary connection that would, if borne out, have important implications.
mesh_terms: D001483:Base Sequence; D004271:DNA, Fungal / Q000235:genetics; D004272:DNA, Mitochondrial / Q000235:genetics*; D005656:Fungal Proteins / Q000235:genetics*; D012367:RNA, Viral / Q000235:genetics; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D014027:Tobacco Mosaic Virus / Q000235:genetics*; D014764:Viral Proteins / Q000235:genetics*
chemical_list: D004271:DNA, Fungal; D004272:DNA, Mitochondrial; D005656:Fungal Proteins; D012367:RNA, Viral; D014764:Viral Proteins