Skibbens Robert V
Department of Biological Sciences, Lehigh University, Bethlehem, Pennsylvania 18015, USA.
Genetics. 2004 Jan;166(1):33-42. doi: 10.1534/genetics.166.1.33.
From the time of DNA replication until anaphase onset, sister chromatids remain tightly paired along their length. Ctf7p/Eco1p is essential to establish sister-chromatid pairing during S-phase and associates with DNA replication components. DNA helicases precede the DNA replication fork and thus will first encounter chromatin sites destined for cohesion. In this study, I provide the first evidence that a DNA helicase is required for proper sister-chromatid cohesion. Characterizations of chl1 mutant cells reveal that CHL1 interacts genetically with both CTF7/ECO1 and CTF18/CHL12, two genes that function in sister-chromatid cohesion. Consistent with genetic interactions, Chl1p physically associates with Ctf7p/Eco1p both in vivo and in vitro. Finally, a functional assay reveals that Chl1p is critical for sister-chromatid cohesion. Within the budding yeast genome, Chl1p exhibits the highest degree of sequence similarity to human CHL1 isoforms and BACH1. Previous studies revealed that human CHLR1 exhibits DNA helicase-like activities and that BACH1 is a helicase-like protein that associates with the tumor suppressor BRCA1 to maintain genome integrity. Our findings document a novel role for Chl1p in sister-chromatid cohesion and provide new insights into the possible mechanisms through which DNA helicases may contribute to cancer progression when mutated.
从DNA复制开始到后期起始，姐妹染色单体在其全长范围内始终紧密配对。Ctf7p/Eco1p对于在S期建立姐妹染色单体配对至关重要，并与DNA复制组件相关联。DNA解旋酶先于DNA复制叉，因此将首先遇到注定要发生黏连的染色质位点。在本研究中，我提供了首个证据，表明DNA解旋酶是正确的姐妹染色单体黏连所必需的。chl1突变细胞的特征表明，CHL1在遗传上与CTF7/ECO1和CTF18/CHL12相互作用，这两个基因在姐妹染色单体黏连中发挥作用。与遗传相互作用一致，Chl1p在体内和体外均与Ctf7p/Eco1p发生物理关联。最后，功能分析表明Chl1p对姐妹染色单体黏连至关重要。在芽殖酵母基因组中，Chl1p与人类CHL1异构体和BACH1具有最高程度的序列相似性。先前的研究表明，人类CHLR1具有类似DNA解旋酶的活性，并且BACH1是一种类似解旋酶的蛋白质，与肿瘤抑制因子BRCA1相关联以维持基因组完整性。我们的研究结果证明了Chl1p在姐妹染色单体黏连中的新作用，并为DNA解旋酶在发生突变时可能促进癌症进展的潜在机制提供了新的见解。
