TOXIC EFFECTS OF EXCESS CLONED CENTROMERES
TOXIC EFFECTS OF EXCESS CLONED CENTROMERES
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DOI：
10.1128/mcb.6.6.2213
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发表时间：
1986-06-01
影响因子：
5.3
通讯作者：
CARBON, J
中科院分区：
文献类型：
--
作者：
FUTCHER, B;CARBON, J
携带酿酒酵母着丝粒的质粒具有一个或两个拷贝数，而其他酵母质粒具有高拷贝数。每个酵母细胞的CEN质粒数量通过用携带不同的独立选择标记的几种不同CEN质粒同时转化细胞而人为地增加。一些宿主细胞携带五种不同的CEN质粒和平均总共13个额外拷贝的CEN3。注意到了若干影响。(i)每个质粒的拷贝数出乎意料地高。（二）.质粒相互不稳定。(iii)培养物中含有许多死细胞。(iv)即使在非选择性培养基中，活宿主细胞的生长也比对照细胞慢。(v)细胞周期在有丝分裂时或有丝分裂前有一个停顿。我们的结论是，过量的着丝粒是有毒的，着丝粒质粒的拷贝数是低的，部分原因是选择对细胞携带多个着丝粒质粒。这种毒性可能是由于着丝粒之间对有限数量的某些因子的竞争引起的，例如，着丝粒结合蛋白、微管或纺锤体极体上的空间。
Plasmids carrying a SAccharomyces cerevisiae centromere have a copy number of one or two, whereas other yeast plasmids have high copy numbers. The number of CEN plasmids per yeast cell was made artificially high by transforming cells simultaneously with several different CEN plasmids carrying different, independently selectable markers. Some host cells carried five different CEN plasmids and an average total of 13 extra copies of CEN3. Several effects were noted. (i) The copy number of each plasmid was unexpectedly high. (ii). The plasmids were mutually unstable. (iii) Cultures contained many dead cells. (iv) The viable host cells grew more slowly than control cells, even in nonselective medium. (v) There was a pause in the cell cycle at or just before mitosis. We conclude that an excess of centromeres is toxic and that the copy number of centromere plasmids is low partly because of selection against cells carrying multiple centromere plasmids. The toxicity may be caused by competition between the centromeres for some factor present in limiting quantities, e.g., centromere-binding protein, microtubules, or space on the spindle pole body.