title: Proteolytic maturation of the 206-kDa nonstructural protein encoded by turnip yellow mosaic virus RNA.
abstract: The longest open reading frame of turnip yellow mosaic virus genomic RNA (ORF-206) encodes a 206-kDa nonstructural protein. The most prominent in vitro translation products of ORF-206 are the full-length p206 and a shorter N-coterminal 150-kDa protein. We have confirmed these assignments by immunoprecipitation of in vitro translation products with antisera raised to N-terminal and C-terminal regions encoded by ORF-206. The mechanism by which the 150-kDa protein arises from ORF-206 was investigated by in vitro translation of deletion and substitution derivatives transcribed from pTYMC, a cDNA clone of TYMV RNA. The following observations demonstrate that the 150-kDa protein and a C-terminal 70-kDa protein arise from ORF-206 by autoproteolysis: (1) Two regions encoded by ORF-206 were necessary for the formation of the 150-kDa protein: a domain between amino acids 555 and 1051, postulated to encode a protease, and the region between amino acids 1253 and 1261, thought to constitute the protease recognition and/or cleavage site. (2) Mutants with substitutions between amino acids 1253 and 1261 that produce low levels of the 150-kDa protein in in vitro translations also have high levels of p206 and low levels of the 70-kDa protein. (3) The rate of formation of the 150-kDa protein is dilution insensitive, suggesting that proteolysis occurs mainly in cis.
authors.affiliation: Department of Agricultural Chemistry and Genetics Program, Oregon State University, Corvallis 97331-6502.
authors.forename: K L
authors.initials: KL
authors.lastname: Bransom
authors.forename: J J
authors.initials: JJ
authors.lastname: Weiland
authors.forename: T W
authors.initials: TW
authors.lastname: Dreher
mesh_terms: D000595:Amino Acid Sequence; D002213:Capsid / Q000235:genetics*; D002872:Chromosome Deletion; D010450:Endopeptidases / Q000378:metabolism; D005814:Genes, Viral; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009029:Mosaic Viruses / Q000235:genetics*; D016297:Mutagenesis, Site-Directed; D016366:Open Reading Frames; D010957:Plasmids; D014176:Protein Biosynthesis; D012367:RNA, Viral / Q000235:genetics*; D015183:Restriction Mapping; D013379:Substrate Specificity; D014158:Transcription, Genetic; D014758:Viral Core Proteins / Q000235:genetics*; D017361:Viral Nonstructural Proteins / Q000235:genetics* / Q000378:metabolism
chemical_list: C088367:150 kDa protein, turnip yellow mosaic virus; C088365:70 kDa protein, turnip yellow mosaic virus; D012367:RNA, Viral; D014758:Viral Core Proteins; D017361:Viral Nonstructural Proteins; D010450:Endopeptidases