Lavoie B D, Tuffo K M, Oh S, Koshland D, Holm C
Department of Embryology, Howard Hughes Medical Institute, Carnegie Institution of Washington, Baltimore, Maryland 21210, USA.
Mol Biol Cell. 2000 Apr;11(4):1293-304. doi: 10.1091/mbc.11.4.1293.
In vitro studies suggest that the Barren protein may function as an activator of DNA topoisomerase II and/or as a component of the Xenopus condensin complex. To better understand the role of Barren in vivo, we generated conditional alleles of the structural gene for Barren (BRN1) in Saccharomyces cerevisiae. We show that Barren is an essential protein required for chromosome condensation in vivo and that it is likely to function as an intrinsic component of the yeast condensation machinery. Consistent with this view, we show that Barren performs an essential function during a period of the cell cycle when chromosome condensation is established and maintained. In contrast, Barren does not serve as an essential activator of DNA topoisomerase II in vivo. Finally, brn1 mutants display additional phenotypes such as stretched chromosomes, aberrant anaphase spindles, and the accumulation of cells with >2C DNA content, suggesting that Barren function influences multiple aspects of chromosome transmission and dynamics.
体外研究表明，Barren蛋白可能作为DNA拓扑异构酶II的激活剂和/或作为非洲爪蟾凝聚素复合物的一个组分发挥作用。为了更好地理解Barren在体内的作用，我们在酿酒酵母中构建了Barren（BRN1）结构基因的条件等位基因。我们发现，Barren是体内染色体凝聚所必需的一种蛋白质，并且它可能作为酵母凝聚机制的一个内在组分发挥作用。与此观点一致，我们发现Barren在细胞周期中建立和维持染色体凝聚的时期发挥着至关重要的作用。相比之下，Barren在体内并非DNA拓扑异构酶II的必需激活剂。最后，brn1突变体表现出其他表型，如染色体拉长、后期纺锤体异常以及DNA含量>2C的细胞积累，这表明Barren的功能影响染色体传递和动态变化的多个方面。
