Efimov V P, Morris N R
Department of Pharmacology, UMDNJ-Robert Wood Johnson Medical School, Piscataway, New Jersey 08854-5635, USA.
Genetics. 1998 May;149(1):101-16. doi: 10.1093/genetics/149.1.101.
Cytoplasmic dynein is a ubiquitously expressed microtubule motor involved in vesicle transport, mitosis, nuclear migration, and spindle orientation. In the filamentous fungus Aspergillus nidulans, inactivation of cytoplasmic dynein, although not lethal, severely impairs nuclear migration. The role of dynein in mitosis and vesicle transport in this organism is unclear. To investigate the complete range of dynein function in A. nidulans, we searched for synthetic lethal mutations that significantly reduced growth in the absence of dynein but had little effect on their own. We isolated 19 sld (synthetic lethality without dynein) mutations in nine different genes. Mutations in two genes exacerbate the nuclear migration defect seen in the absence of dynein. Mutations in six other genes, including sldA and sldB, show a strong synthetic lethal interaction with a mutation in the mitotic kinesin bimC and, thus, are likely to play a role in mitosis. Mutations in sldA and sldB also confer hypersensitivity to the microtubule-destabilizing drug benomyl. sldA and sldB were cloned by complementation of their mutant phenotypes using an A. nidulans autonomously replicating vector. Sequencing revealed homology to the spindle assembly checkpoint genes BUB1 and BUB3 from Saccharomyces cerevisiae. Genetic interaction between dynein and spindle assembly checkpoint genes, as well as other mitotic genes, indicates that A. nidulans dynein plays a role in mitosis. We suggest a model for dynein motor action in A. nidulans that can explain dynein involvement in both mitosis and nuclear distribution.
胞质动力蛋白是一种广泛表达的微管马达蛋白，参与囊泡运输、有丝分裂、核迁移和纺锤体定向。在丝状真菌构巢曲霉中，胞质动力蛋白失活虽不致死，但会严重损害核迁移。动力蛋白在该生物体有丝分裂和囊泡运输中的作用尚不清楚。为了研究构巢曲霉中动力蛋白功能的完整范围，我们寻找了合成致死突变，这些突变在没有动力蛋白的情况下会显著降低生长，但自身影响很小。我们在九个不同基因中分离出19个sld（无动力蛋白时的合成致死）突变。两个基因的突变加剧了在没有动力蛋白时观察到的核迁移缺陷。其他六个基因的突变，包括sldA和sldB，与有丝分裂驱动蛋白bimC的突变表现出强烈的合成致死相互作用，因此可能在有丝分裂中起作用。sldA和sldB的突变也使细胞对微管不稳定药物苯菌灵敏感。通过使用构巢曲霉自主复制载体互补其突变表型，克隆了sldA和sldB。测序显示与酿酒酵母的纺锤体组装检查点基因BUB1和BUB3具有同源性。动力蛋白与纺锤体组装检查点基因以及其他有丝分裂基因之间的遗传相互作用表明，构巢曲霉动力蛋白在有丝分裂中起作用。我们提出了一个构巢曲霉中动力蛋白马达作用的模型，该模型可以解释动力蛋白在有丝分裂和核分布中的作用。
