Autoactivation of proteinase A initiates activation of yeast vacuolar zymogens.
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.
van den Hazel
H B
HB
Department of Yeast Genetics, Carlsberg Laboratory, Copenhagen, Denmark.
Kielland-Brandt
M C
MC
Winther
J R
JR
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*
D003062:Codon; D004792:Enzyme Precursors; D029701:Saccharomyces cerevisiae Proteins; C022325:aspartic proteinase A; C499267:PEP4 protein, S cerevisiae; D016282:Aspartic Acid Endopeptidases