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Negative regulation of mitosis in fission yeast by catalytically inactive pyp1 and pyp2 mutants

Author:
Hannig, G., Ottilie, S., Erikson, R.L.
Source:
Proceedings of the National Academy of Sciences of the United States of America 1994 v.91 no.21 pp. 10084-10088
ISSN:
0027-8424
Subject:
Saccharomycetales, mitosis, mutants, phosphoprotein phosphatase, Schizosaccharomyces pombe, protein-tyrosine-phosphatase
Abstract:
The Schizosaccharomyces pombe genes pyp1+ and pyp2+ encode protein tyrosine phosphatases (PTPases) that act as negative regulators of mitosis upstream of the wee1+/mik1+ pathway. Here we provide evidence that pyp1+ and pyp2+ function independently of cdr1+(nim1+) in the inhibition of mitosis and that the wee1 kinase is not a direct substrate of either PTPase. In a pyp1::ura4 cdc25-22 genetic background, overexpression of either the N-terminal domain of pyp1+ or a catalytically inactive mutant, pyp1C470S, causes cell cycle arrest. This phenotype reverses the suppression of a cdc25 temperature-sensitive mutation at 35 degrees caused by a pyp1 disruption. Furthermore, pyp1C470S and a catalytically inactive mutant of pyp2, pyp2C630S, induce mitotic delay as do their wild-type counterparts. Analysis of pyp1+ and pyp2+ further reveals that the in vitro PTPase activity of pyp1 and pyp2, as well as their biological activity, is dependent on the presence of N-terminal sequences that are not normally considered part of PTPase catalytic domains.
Agid:
2355460