Schwartz K, Richards K, Botstein D
Department of Genetics, Stanford University School of Medicine, Stanford, California 94305, USA.
Mol Biol Cell. 1997 Dec;8(12):2677-91. doi: 10.1091/mbc.8.12.2677.
A previously uncharacterized yeast gene (YER016w) that we have named BIM1 (binding to microtubules) was obtained from a two-hybrid screen of a yeast cDNA library using as bait the entire coding sequence of TUB1 (encoding alpha-tubulin). Deletion of BIM1 results in a strong bilateral karyogamy defect, hypersensitivity to benomyl, and aberrant spindle behavior, all phenotypes associated with mutations affecting microtubules in yeast, and inviability at extreme temperatures (i.e., >/=37 degrees C or </=14 degrees C). Overexpression of BIM1 in wild-type cells is lethal. A fusion of Bim1p with green fluorescent protein that complements the bim1Delta phenotypes allows visualization in vivo of both intranuclear spindles and extranuclear microtubules in otherwise wild-type cells. A bim1 deletion displays synthetic lethality with deletion alleles of bik1, num1, and bub3 as well as a limited subset of tub1 conditional-lethal alleles. A systematic study of 51 tub1 alleles suggests a correlation between specific failure to interact with Bim1p in the two-hybrid assay and synthetic lethality with the bim1Delta allele. The sequence of BIM1 shows substantial similarity to sequences from organisms across the evolutionary spectrum. One of the human homologues, EB1, has been reported previously as binding APC, itself a microtubule-binding protein and the product of a gene implicated in the etiology of human colon cancer.
我们从酵母cDNA文库的双杂交筛选中获得了一个以前未被鉴定的酵母基因（YER016w），我们将其命名为BIM1（与微管结合），该筛选以TUB1（编码α-微管蛋白）的完整编码序列作为诱饵。BIM1的缺失导致强烈的双侧核融合缺陷、对苯菌灵的超敏反应和异常的纺锤体行为，所有这些表型都与影响酵母微管的突变相关，并且在极端温度下（即≥37℃或≤14℃）无法存活。在野生型细胞中过表达BIM1是致死的。Bim1p与绿色荧光蛋白的融合能够互补bim1Δ表型，从而可以在体内观察野生型细胞中的核内纺锤体和核外微管。bim1缺失与bik1、num1和bub3的缺失等位基因以及tub1条件致死等位基因的一个有限子集表现出合成致死性。对51个tub1等位基因的系统研究表明，在双杂交试验中与Bim1p特异性相互作用失败与与bim1Δ等位基因的合成致死性之间存在相关性。BIM1的序列与整个进化谱系中生物体的序列显示出高度相似性。其中一个人类同源物EB1，先前已被报道可结合APC，APC本身是一种微管结合蛋白，也是一个与人类结肠癌病因相关的基因的产物。
