Proteinase Mutants of Saccharomyces Cerevisiaei

Fifty-nine mutants with reduced ability to cleave the chymotrypsin substrate N-acetyl-DL-phenylalanine P-naphthyl ester have been isolated in S. cerevisiae. All have reduced levels of one o r more of the three well-characterized proteinases in yeast. All have reduced levels of proteinase C (carboxypeptidase Y). These mutations define 16 complementation groups. HREE proteinases that have been characterized in yeast are proteinases A Tand B (HATA, HAYASHI and Do1 1967a,b; LENNEY and DALBEC 1967; SAHEKI and HOLZER 1974) and proteinase C, also called carboxypeptidase Y (DoI, HAYASHI. and HATA 1967; HATA, HAYASHI, and Do1 196713; HAYASHI, AIBARA, and HATA 1970; HAYASHI, MOORE and STEIN 1973; KUHN, WALSH and NEURATH 1974). Macromolecular inhibitors for each of these proteinases are found intracellularly (BETZ, HINZE and HOLZER 1974; MATERN, HOFFMAN and HOLZER 1974; SAHEKI, MATSUDA and HOIZER 1974). The proteinases appear to be localized in vesicles (CABIB, ULANE and BOWERS 1973; HASILIK, MULLER and HOLZER 1974; LENNY et al. 1974; MATERN, BETZ and HOLZER 1974), whereas the inhibitors for proteinase B (HASILIK, MULLER and HOLZER 1974; LENNEY et al. 1974; MATERN. BETZ and HOLZER 1974), proteinase A (LENNEY et al. 1974; MATERN, BETZ and HOLZER 1974) and proteinase C (MATERN, BETZ and HOLZER 1974) are localized in the cytoplasm. Based on in vitro observations, proteinases A and B have been implicated in inactivation of tryptophan synthetase (KATSUNAMA et al. 1972; SAHEKI and HOLZER 1974; SAHEKI and HOLZER 1975), activation of chitin synthetase (CABIB and FARKAS 1971; CABIB and ULANE 1973; CABIB, ULANE and BOWERS 1974; HASILIK and HOLZER 1973) , and proteinase B has been postulated to participate in septation in yeast (CABIB, ULANE and BOWERS 1974). Protein degradation and turnover has been shown to occur when cells undergo meiosis and sporulation ( ESPOSITO et al. 1969; HOPPER et al. 1974) and the levels of the three proteinases rise when cells sporulate (BETZ and WEISER 1976; KLAR and HALVORSON 1975; CHEN and MILLER 1968). The role of these three proteinases in the physiology of the cell and in the transition between cell states (mitosis and meiosis) should be clarified if mutants ' Supported hy Public Health Service Research Career Development Awards 1 KO4 AM36710 and 1 KO4 AM00050, and Public Health Service Research Grants 5 R01 AM18090 and AM14254. Genetics 85 : 23-33 January, 1977