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The proteinase yscA‐inhibitor, I A 3 , gene Studies of cytoplasmic proteinase inhibitor deficiency on yeast physiology
Author(s) -
Schu Peter,
Wolf Dieter H.
Publication year - 1991
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(91)80558-k
Subject(s) - mutant , saccharomyces cerevisiae , biology , mutagenesis , yeast , microbiology and biotechnology , biochemistry , gene , cytoplasm , oligonucleotide
The gene of the proteinase yscA inhibitor I A 3 , , of the yeast Saccharamyces cerevisiae was isolated by oligonucleotide screening of a genomic DNA library and sequenced. The gene codes for a single protein of 68 amino acids. The structural gene was deleted in vitro by oligonucleotide‐site‐directed mutagenesis. The mutated allele was introduced via homologous recombination into the genome of wild‐type yeast and into the genome of a yeast mutant, which lacks the second cytoplasmic proteinase‐inhibitor, I B 2 . The deficiency of either or of both inhibitors has no effect on the cell viability under various physiological conditions. The inhibitor mutants, however, show an increase in the general in vivo protein degradation rate. The I A 3 mutant has a 2–3‐fold increased protein degradation rate in the first 6 h after a shift from rich medium onto starvation‐medium, whereas the I B 2 mutant shows a constantly increased degradation rate of 20–50% under the same conditions. The inhibitor double null mutant has the same protein degradation rate as the I A 3 null mutant. These results suggest an in vivo interaction between the vacuolor endopeptidases and their cytoplasmic inhibitors.