Goes F S, Martin J
Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, Providence, Rhode Island 02912, USA.
Eur J Biochem. 2001 Apr;268(8):2281-9. doi: 10.1046/j.1432-1327.2001.02105.x.
The Wee1 protein kinase negatively regulates entry into mitosis by mediating the inhibitory tyrosine phosphorylation of Cdc2-cyclin B kinase. The stability and activity of Wee1 from the fission yeast Schizosaccharomyces pombe is critically dependent on functional Hsp90 chaperones. Here we identify two related tyrosine protein kinases, Mik1 from fission yeast and its Saccharomyces cerevisiae homolog Swe1, as Hsp90 substrates and show that the kinase domain is sufficient to mediate this interaction. Morphological and biochemical defects arising from overexpression of the kinases in fission yeast are suppressed in the conditional Hsp90 mutant swo1-26. A subset of all three kinases is associated with the Hsp90 cochaperones cyclophilin 40 and p23. Under conditions of impaired chaperone function or treatment with the Hsp90 inhibitory drug geldanamycin, intracellular levels of the kinases are reduced and the proteins become rapidly degraded by the proteasome machinery, indicating that Wee1, Mik1 and Swe1 require Hsp90 heterocomplexes for their stability and maintenance of function.
Wee1蛋白激酶通过介导Cdc2-细胞周期蛋白B激酶的抑制性酪氨酸磷酸化来负调控进入有丝分裂的过程。来自裂殖酵母粟酒裂殖酵母的Wee1的稳定性和活性严重依赖于功能性Hsp90伴侣蛋白。在此，我们鉴定出两种相关的酪氨酸蛋白激酶，来自裂殖酵母的Mik1及其酿酒酵母同源物Swe1，作为Hsp90底物，并表明激酶结构域足以介导这种相互作用。在条件性Hsp90突变体swo1-26中，裂殖酵母中激酶过表达引起的形态学和生化缺陷得到抑制。所有这三种激酶的一个亚群与Hsp90共伴侣蛋白亲环蛋白40和p23相关联。在伴侣蛋白功能受损或用Hsp90抑制药物格尔德霉素处理的条件下，激酶的细胞内水平降低，并且蛋白质被蛋白酶体机制迅速降解，这表明Wee1、Mik1和Swe1需要Hsp90异源复合物来维持其稳定性和功能。
