Processing of a pestivirus protein by a cellular protease specific for light chain 3 of microtubule-associated proteins.
The genome of the cytopathogenic (cp) bovine viral diarrhea virus (BVDV) JaCP contains a cellular insertion coding for light chain 3 (LC3) of microtubule-associated proteins, the mammalian homologue of yeast Aut7p/Apg8p. The cellular insertion induces cp BVDV-specific processing of the viral polyprotein by a cellular cysteine protease homologous to the known yeast protease Aut2p/Apg4p. Three candidate bovine protease genes were identified on the basis of the sequence similarity of their products with the Saccharomyces cerevisiae enzyme. The search for a system for functional testing of these putative LC3-specific proteases revealed that the components involved in this processing have been highly conserved during evolution, so that the substrate derived from a mammalian virus is processed in cells of mammalian, avian, fish, and insect origin, as well as in rabbit reticulocyte lysate, but not in wheat germ extracts. Moreover, two of these proteases and a homologous protein from chickens were able to rescue the defect of a yeast AUT2 deletion mutant. In coexpression experiments with yeast and wheat germ extracts one of the bovine proteases and the corresponding enzyme from chickens were able to process the viral polyprotein containing LC3. Northern blots showed that bovine viral diarrhea virus infection of cells has no significant influence on the expression of either LC3 or its protease, bAut2B2. However, LC3-specific processing of the viral polyprotein containing the cellular insertion is essential for replication of the virus since mutants with changes in the LC3 insertion significantly affecting processing at the LC3/NS3 site were not viable.
Fricke
Jens
J
Institut für Immunologie, Federal Research Center for Virus Diseases of Animals, P.O. Box 1149, D-72001 Tübingen, Germany.
Voss
Christiane
C
Thumm
Michael
M
Meyers
Gregor
G
D000595:Amino Acid Sequence; D000818:Animals; D000071190:Autophagy-Related Protein 8 Family; D002352:Carrier Proteins / Q000502:physiology; D002417:Cattle; D002460:Cell Line; D002645:Chickens; D001908:Diarrhea Viruses, Bovine Viral / Q000737:chemistry* / Q000502:physiology; D010450:Endopeptidases / Q000502:physiology*; D008869:Microtubule-Associated Proteins / Q000378:metabolism*; D008969:Molecular Sequence Data; D010447:Peptide Hydrolases; D020365:RNA Helicases; D029701:Saccharomyces cerevisiae Proteins; D017361:Viral Nonstructural Proteins / Q000378:metabolism; D014764:Viral Proteins / Q000378:metabolism*; D012697:Serine Endopeptidases; D043583:Nucleoside-Triphosphatase; D053487:DEAD-box RNA Helicases; D000085242:Viral Proteases
D000071190:Autophagy-Related Protein 8 Family; D002352:Carrier Proteins; D010450:Endopeptidases; D008869:Microtubule-Associated Proteins; D010447:Peptide Hydrolases; D020365:RNA Helicases; D029701:Saccharomyces cerevisiae Proteins; D017361:Viral Nonstructural Proteins; D014764:Viral Proteins; C113757:ATG8 protein, S cerevisiae; C086730:p80 protein, bovine viral diarrhea virus; D012697:Serine Endopeptidases; D043583:Nucleoside-Triphosphatase; D053487:DEAD-box RNA Helicases; D000085242:Viral Proteases