A second proteinase encoded by a plant potyvirus genome

EMBO J. 1989 Feb;8(2):365-70.


The RNA genome of tobacco etch virus (TEV) encodes a large polyprotein precursor that is processed to mature proteins by virus-specific proteinases. Cleavage sites located within the carboxyl-terminal two-thirds of the polyprotein are processed by a TEV-encoded 49 kd proteinase, while the enzyme(s) responsible for cleaving the remaining sites has not been found. In this study, a second TEV-encoded proteinase has been identified based on cell-free expression of defined RNA transcripts. The boundaries of this proteinase have been delineated by deletion analysis and site-directed mutagenesis. The proteolytically active domain has been localized to the carboxyl-terminal half of the 56 kd aphid-transmission helper component. A cleavage site that is recognized by this proteinase has been identified in the polyprotein adjacent to the carboxyl-terminus of the enzyme, and the proteinase appears to cleave by an autocatalytic mechanism. Proteolysis in vitro occurs between a Gly-Gly dipeptide as determined by radiochemical sequencing at the amino-terminus of the proteolytic product.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Binding Sites
  • Endopeptidases / genetics*
  • Endopeptidases / metabolism
  • Genes, Viral
  • Molecular Sequence Data
  • Mutation
  • Plant Viruses / genetics*
  • Plant Viruses / metabolism
  • Protein Precursors / metabolism
  • Protein Processing, Post-Translational


  • Protein Precursors
  • Endopeptidases