Baker R E, Masison D C
Department of Molecular Genetics and Microbiology, University of Massachusetts Medical School, Worcester 01655.
Mol Cell Biol. 1990 Jun;10(6):2458-67. doi: 10.1128/mcb.10.6.2458-2467.1990.
CP1 is a sequence-specific DNA-binding protein of the yeast Saccharomyces cerevisiae which recognizes the highly conserved DNA element I (CDEI) of yeast centromeres. We cloned and sequenced the gene encoding CP1. The gene codes for a protein of molecular weight 39,400. When expressed in Escherichia coli, the CP1 gene directed the synthesis of a CDEI-binding protein having the same gel mobility as purified yeast CP1. We have given the CP1 gene the genetic designation CEP1 (centromere protein 1). CEP1 was mapped and found to reside on chromosome X, 2.0 centimorgans from SUP4. Strains were constructed in which most of CEP1 was deleted. Such strains lacked detectable CP1 activity and were viable; however, CEP1 gene disruption resulted in a 35% increase in cell doubling time and a ninefold increase in the rate of mitotic chromosome loss. An unexpected consequence of CP1 gene disruption was methionine auxotrophy genetically linked to cep1. This result and the recent finding that CDEI sites in the MET25 promoter are required to activate transcription (D. Thomas, H. Cherest, and Y. Surdin-Kerjan, J. Mol. Biol. 9:3292-3298, 1989) suggest that CP1 is both a kinetochore protein and a transcription factor.
CP1是酿酒酵母的一种序列特异性DNA结合蛋白，它能识别酵母着丝粒中高度保守的DNA元件I（CDEI）。我们克隆并测序了编码CP1的基因。该基因编码一种分子量为39400的蛋白质。当在大肠杆菌中表达时，CP1基因指导合成一种与纯化的酵母CP1具有相同凝胶迁移率的CDEI结合蛋白。我们给CP1基因赋予了遗传命名CEP1（着丝粒蛋白1）。CEP1被定位并发现位于X染色体上，距离SUP4有2.0厘摩。构建了大部分CEP1被缺失的菌株。这些菌株缺乏可检测到的CP1活性，但仍能存活；然而，CEP1基因的破坏导致细胞倍增时间增加35%，有丝分裂染色体丢失率增加9倍。CP1基因破坏的一个意外后果是与cep1遗传连锁的甲硫氨酸营养缺陷型。这一结果以及最近发现MET25启动子中的CDEI位点是激活转录所必需的（D.托马斯、H.谢雷斯特和Y.苏尔丹 - 凯尔让，《分子生物学杂志》9:3292 - 3298，1989）表明CP1既是一种动粒蛋白也是一种转录因子。
