Sparks C A, Morphew M, McCollum D
Department of Molecular Genetics and Microbiology, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA.
J Cell Biol. 1999 Aug 23;146(4):777-90. doi: 10.1083/jcb.146.4.777.
The fission yeast Schizosaccharomyces pombe divides by medial fission through the use of an actomyosin contractile ring. Precisely at the end of anaphase, the ring begins to constrict and the septum forms. Proper coordination of cell division with mitosis is crucial to ensure proper segregation of chromosomes to daughter cells. The Sid2p kinase is one of several proteins that function as part of a novel signaling pathway required for initiation of medial ring constriction and septation. Here, we show that Sid2p is a component of the spindle pole body at all stages of the cell cycle and localizes transiently to the cell division site during medial ring constriction and septation. A medial ring and an intact microtubule cytoskeleton are required for the localization of Sid2p to the division site. We have established an in vitro assay for measuring Sid2p kinase activity, and found that Sid2p kinase activity peaks during medial ring constriction and septation. Both Sid2p localization to the division site and activity depend on the function of all of the other septation initiation genes: cdc7, cdc11, cdc14, sid1, spg1, and sid4. Thus, Sid2p, a component of the spindle pole body, by virtue of its transient localization to the division site, appears to determine the timing of ring constriction and septum delivery in response to activating signals from other Sid gene products.
裂殖酵母粟酒裂殖酵母通过肌动球蛋白收缩环进行中间分裂。恰好在后期结束时，环开始收缩，隔膜形成。细胞分裂与有丝分裂的正确协调对于确保染色体正确分离到子细胞中至关重要。Sid2p激酶是作为中间环收缩和隔膜形成起始所需的新型信号通路一部分发挥作用的几种蛋白质之一。在这里，我们表明Sid2p在细胞周期的所有阶段都是纺锤极体的一个组成部分，并且在中间环收缩和隔膜形成期间短暂定位于细胞分裂位点。Sid2p定位于分裂位点需要中间环和完整的微管细胞骨架。我们建立了一种体外测定法来测量Sid2p激酶活性，发现Sid2p激酶活性在中间环收缩和隔膜形成期间达到峰值。Sid2p定位于分裂位点和活性都依赖于所有其他隔膜形成起始基因的功能：cdc7、cdc11、cdc14、sid1、spg1和sid4。因此，Sid2p作为纺锤极体的一个组成部分，凭借其短暂定位于分裂位点，似乎根据来自其他Sid基因产物的激活信号来确定环收缩和隔膜形成的时间。
