title: Autoactivation of proteinase A initiates activation of yeast vacuolar zymogens.
abstract: The Saccharomyces cerevisiae PEP4 gene encodes proteinase A, an aspartyl protease. pep4 mutants are defective in the activation of many vacuolar hydrolases, including proteinase B. We have expressed a pep4 mutation which directs the accumulation of pro-proteinase A with a defective active site. Co-expression with PEP4 leads to normal processing, i.e. the mutant zymogen is functional as a substrate for the maturation reaction in trans. We conclude that wild-type pro-proteinase A has the ability to mediate its own activation. Elimination of the co-expressed PEP4 gene did not effectively stop the processing of the mutant zymogen, owing to a strong, proteinase-B-dependent, phenotypic lag. In a proteinase-B-negative strain, processing of pro-proteinase A led to an active form of a higher molecular mass than the normal mature form.
authors.affiliation: Department of Yeast Genetics, Carlsberg Laboratory, Copenhagen, Denmark.
authors.forename: H B
authors.initials: HB
authors.lastname: van den Hazel
authors.forename: M C
authors.initials: MC
authors.lastname: Kielland-Brandt
authors.forename: J R
authors.initials: JR
authors.lastname: Winther
mesh_terms: D000483:Alleles; D000595:Amino Acid Sequence; D016282:Aspartic Acid Endopeptidases / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D001665:Binding Sites; D003062:Codon; D004789:Enzyme Activation; D004792:Enzyme Precursors / Q000378:metabolism*; D005800:Genes, Fungal; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D010641:Phenotype; D010957:Plasmids; D016133:Polymerase Chain Reaction; D011499:Protein Processing, Post-Translational; D015183:Restriction Mapping; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins; D014617:Vacuoles / Q000201:enzymology*
chemical_list: D003062:Codon; D004792:Enzyme Precursors; D029701:Saccharomyces cerevisiae Proteins; C022325:aspartic proteinase A; C499267:PEP4 protein, S cerevisiae; D016282:Aspartic Acid Endopeptidases