The condensin complex governs chromosome condensation and mitotic transmission of rDNA.
The condensin complex governs chromosome condensation and mitotic transmission of rDNA.
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DOI：
10.1083/jcb.149.4.811
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发表时间：
2000-05-15
期刊：
影响因子：
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通讯作者：
Strunnikov A
中科院分区：
文献类型：
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作者：
Freeman L;Aragon-Alcaide L;Strunnikov A
我们已经鉴定了5个编码酿酒酵母凝聚蛋白成分的基因。所有的基因都是细胞生存所必需的，并编码在体内形成复合物的蛋白质。我们鉴定了编码该复合体核心亚基的基因smc2-8和smc4-1的新突变等位基因。SMC2和SMC4都是染色体后期传递所必需的。这些基因的突变导致在建立独特的（染色体VIII臂）和重复的（rDNA）基因组区域凝聚缺陷，但不损害姐妹染色单体内聚。Smc4p融合到绿色荧光蛋白的体内定位显示，在酿酒酵母中，凝缩蛋白复合物在细胞周期的G2/M期集中在rDNA区域。与中心点周围和远端臂区分离相比，有丝分裂中的rDNA分离在smc2和smc4突变体中延迟和/或停滞。携带rDNA易位的染色体III的有丝分裂传递在smc2和smc4突变体中受损。因此，酿酒酵母中的凝缩蛋白复合物在rDNA位点的有丝分裂分离中具有特殊的功能。染色质免疫沉淀（ChIP）分析显示凝缩蛋白在体内与rDNA存在物理关联。因此，rDNA阵列是第一个在体内被凝缩蛋白特异性结合的DNA序列。讨论了酿酒酵母高阶染色体结构的生物学作用。
We have characterized five genes encoding condensin components in Saccharomyces cerevisiae. All genes are essential for cell viability and encode proteins that form a complex in vivo. We characterized new mutant alleles of the genes encoding the core subunits of this complex, smc2-8 and smc4-1. Both SMC2 and SMC4 are essential for chromosome transmission in anaphase. Mutations in these genes cause defects in establishing condensation of unique (chromosome VIII arm) and repetitive (rDNA) regions of the genome but do not impair sister chromatid cohesion. In vivo localization of Smc4p fused to green fluorescent protein showed that, unexpectedly, in S. cerevisiae the condensin complex concentrates in the rDNA region at the G2/M phase of the cell cycle. rDNA segregation in mitosis is delayed and/or stalled in smc2 and smc4 mutants, compared with separation of pericentromeric and distal arm regions. Mitotic transmission of chromosome III carrying the rDNA translocation is impaired in smc2 and smc4 mutants. Thus, the condensin complex in S. cerevisiae has a specialized function in mitotic segregation of the rDNA locus. Chromatin immunoprecipitation (ChIP) analysis revealed that condensin is physically associated with rDNA in vivo. Thus, the rDNA array is the first identified set of DNA sequences specifically bound by condensin in vivo. The biological role of higher-order chromosome structure in S. cerevisiae is discussed.