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A Bub2p‐dependent spindle checkpoint pathway regulates the Dbf2p kinase in budding yeast
Author(s) -
Fesquet Didier,
Fitzpatrick Patrick J.,
Johnson Anthony L.,
Kramer Kate M.,
Toyn Jeremy H.,
Johnston Leland H.
Publication year - 1999
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1093/emboj/18.9.2424
Subject(s) - spindle checkpoint , biology , anaphase promoting complex , microbiology and biotechnology , g2 m dna damage checkpoint , mitotic exit , anaphase , kinetochore , spindle pole body , aurora b kinase , spindle apparatus , polo like kinase , mitosis , cell cycle checkpoint , cell cycle , genetics , cell division , cell , chromosome , gene
Exit from mitosis in all eukaroytes requires inactivation of the mitotic kinase. This occurs principally by ubiquitin‐mediated proteolysis of the cyclin subunit controlled by the anaphase‐promoting complex (APC). However, an abnormal spindle and/or unattached kinetochores activates a conserved spindle checkpoint that blocks APC function. This leads to high mitotic kinase activity and prevents mitotic exit. DBF2 belongs to a group of budding yeast cell cycle genes that when mutated prevent cyclin degradation and block exit from mitosis. DBF2 encodes a protein kinase which is cell cycle regulated, peaking in metaphase–anaphase B/telophase, but its function remains unknown. Here, we show the Dbf2p kinase activity to be a target of the spindle checkpoint. It is controlled specifically by Bub2p, one of the checkpoint components that is conserved in fission yeast and higher eukaroytic cells. Significantly, in budding yeast, Bub2p shows few genetic or biochemical interactions with other members of the spindle checkpoint. Our data now point to the protein kinase Mps1p triggering a new parallel branch of the spindle checkpoint in which Bub2p blocks Dbf2p function.