Arellano M, Durán A, Pérez P
Instituto de Microbiología Bioquímica, Consejo Superior de Investigaciones Científicas and Universidad de Salamanca, Edificio Departamental, Spain.
EMBO J. 1996 Sep 2;15(17):4584-91.
The Schizosaccharomyces pombe Cdc42 and Rho1 GTPases were tested for their ability to complement the cwg2-1 mutant phenotype of a decrease in (1-3)beta-D-glucan synthase activity when grown at the non-permissive temperature. Only Rho1 is able to partly complement the defect in glucan synthase associated with the cwg2-1 mutation. Moreover, overexpression of the rho1 gene in wild-type S.pombe cells causes aberrant morphology with loss of polarity and cells with several septa. Under this condition (1-3)beta-D-glucan synthase activity is increased four times, but is still dependent on GTP. When S.pombe is transformed with constitutively active rho1 mutant alleles (rho1-G15V or rho1-Q64L), cells stop growing and show a very thick cell wall with hardly any septum. Under this condition the level of (1-3)beta-D-glucan synthase activity is at least 20 times higher than wild-type and is independent of GTP. Neither cdc42+ nor the cdc42-V12G or cdc42-Q61L constitutively active mutant alleles affect (1-3)beta-D-glucan synthase activity when overexpressed in S.pombe. Cells overproducing Rho1 are hypersensitive to inhibitors of cell wall biosynthesis or to cell wall degrading enzymes. We conclude that Rho1 GTPase directly activates (1-3)beta-D-glucan synthase and regulates S.pombe morphogenesis.
对粟酒裂殖酵母的Cdc42和Rho1 GTP酶进行了测试，以检测它们在非允许温度下生长时，对cwg2-1突变体表型（(1-3)β-D-葡聚糖合酶活性降低）的互补能力。只有Rho1能够部分互补与cwg2-1突变相关的葡聚糖合酶缺陷。此外，在野生型粟酒裂殖酵母细胞中过表达rho1基因会导致异常形态，细胞极性丧失且出现多个隔膜。在此条件下，(1-3)β-D-葡聚糖合酶活性增加了四倍，但仍依赖于GTP。当用组成型活性rho1突变等位基因（rho1-G15V或rho1-Q64L）转化粟酒裂殖酵母时，细胞停止生长并显示出非常厚的细胞壁，几乎没有隔膜。在此条件下，(1-3)β-D-葡聚糖合酶活性水平比野生型至少高20倍，且不依赖于GTP。当在粟酒裂殖酵母中过表达时，cdc42+以及cdc42-V12G或cdc42-Q61L组成型活性突变等位基因均不影响(1-3)β-D-葡聚糖合酶活性。过量产生Rho1的细胞对细胞壁生物合成抑制剂或细胞壁降解酶高度敏感。我们得出结论，Rho1 GTP酶直接激活(1-3)β-D-葡聚糖合酶并调节粟酒裂殖酵母的形态发生。
