The polarity and dynamics of microtubule assembly in the budding yeast Saccharomyces cerevisiae
The polarity and dynamics of microtubule assembly in the budding yeast Saccharomyces cerevisiae
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DOI：
10.1038/71357
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发表时间：
2000-01-01
影响因子：
21.3
通讯作者：
Salmon, ED
中科院分区：
文献类型：
--
作者：
Maddox, PS;Bloom, KS;Salmon, ED
酿酒酵母的微管组装始于核膜中的纺锤体极体(SPBS)内。微管正端被认为组织在SPBS的远端，而负端则在近端。关于微管马达蛋白在微管组装的力产生和调节中的作用的几个假说认为，微管组装和拆卸发生在正端和负端。在这里，我们分析了在表达绿色荧光蛋白的单倍体酵母细胞中相对于SPBS的微管组装，在整个细胞周期中，微管亚基α-微管蛋白融合，细胞质星形微管上的荧光斑点分析表明，在负端没有可检测到的组装或拆卸。激光-光漂白后，中期纺锤体恢复了约63%的漂白荧光，半衰期约为1分钟。后期开始后，极间纺锤体中的光漂白标记持续存在，不相对于SPBS移动，后期，细长的纺锤体在微管正端解体，这些结果表明，对于星形和后期极间微管，可能还有中期纺锤体微管，微管的组装和拆解发生在正端，而不是负端。
Microtubule assembly in Saccharomyces cerevisiae is initiated from sites within spindle pole bodies (SPBs) in the nuclear envelope. Microtubule plus ends are thought to be organized distal to the SPBs, while minus ends are proximal. Several hypotheses for the function of microtubule motor proteins in force generation and regulation of microtubule assembly propose that assembly and disassembly occur at minus ends as well as at plus ends. Here we analyse microtubule assembly relative to the SPBs in haploid yeast cells expressing green fluorescent protein fused to alpha-tubulin, a microtubule subunit, Throughout the cell cycle, analysis of fluorescent speckle marks on cytoplasmic astral microtubules reveals that there is no detectable assembly or disassembly at minus ends. After laser-photobleaching, metaphase spindles recover about 63% of the bleached fluorescence, with a half-life of about 1 minute. After anaphase onset, photobleached marks in the interpolar spindle are persistent and do not move relative to the SPBs, In late anaphase, the elongated spindles disassemble at the microtubule plus ends, These results show for astral and anaphase interpolar spindle microtubules, and possibly for metaphase spindle microtubules, that microtubule assembly and disassembly occur at plus, and not minus, ends.