title: Characterization of a protein from Rice tungro spherical virus with serine proteinase-like activity.
abstract: The RNA genome of Rice tungro spherical virus (RTSV) is predicted to be expressed as a large polyprotein precursor (Shen et al., Virology 193, 621-630, 1993 ). The polyprotein is processed by at least one virus-encoded protease located adjacent to the C-terminal putative RNA polymerase which shows sequence similarity to viral serine-like proteases. The catalytic activity of this protease was explored using in vitro transcription/translation systems. Besides acting in cis, the protease had activity in trans on precursors containing regions of the 3' half of the polyprotein but did not process a substrate consisting of a precursor of the coat proteins. The substitution mutation of Asp(2735) of the RTSV polyprotein had no effect on proteolysis; however, His(2680), Glu(2717), Cys(2811) and His(2830) proved to be essential for catalytic activity and could constitute the catalytic centre and/or substrate-binding pocket of the RTSV 3C-like protease.
authors.affiliation: John Innes Centre, Department of Metabolic Biology1 and Department of Disease and Stress Biology2, Norwich Research Park, Norwich NR4 7UH, UK.
authors.forename: Vera
authors.initials: V
authors.lastname: Thole
authors.affiliation: John Innes Centre, Department of Metabolic Biology1 and Department of Disease and Stress Biology2, Norwich Research Park, Norwich NR4 7UH, UK.
authors.forename: Roger
authors.initials: R
authors.lastname: Hull
mesh_terms: D000086042:3C Viral Proteases; D003546:Cysteine Endopeptidases / Q000378:metabolism; D012275:Oryza / Q000821:virology*; D020815:Polyproteins / Q000378:metabolism*; D011498:Protein Precursors / Q000378:metabolism; D012697:Serine Endopeptidases / Q000378:metabolism*; D014158:Transcription, Genetic; D014764:Viral Proteins / Q000378:metabolism*; D019193:Waikavirus / Q000201:enzymology* / Q000235:genetics
chemical_list: D020815:Polyproteins; D011498:Protein Precursors; D014764:Viral Proteins; D012697:Serine Endopeptidases; D003546:Cysteine Endopeptidases; D000086042:3C Viral Proteases