13S凝缩蛋白通过ATP依赖方式使DNA产生正超螺旋：对染色体凝聚的生化意义

ATP-dependent positive supercoiling of DNA by 13S condensin: a biochemical implication for chromosome condensation.

作者信息

Kimura K, Hirano T

机构信息

Cold Spring Harbor Laboratory, New York 11724, USA.

出版信息

Cell. 1997 Aug 22;90(4):625-34. doi: 10.1016/s0092-8674(00)80524-3.

DOI:10.1016/s0092-8674(00)80524-3

PMID:9288743

Abstract

13S condensin is a five-subunit protein complex that plays a central role in mitotic chromosome condensation in Xenopus egg extracts. Two core subunits of this complex, XCAP-C and XCAP-E, belong to an emerging family of putative ATPases, the SMC family. We report here that 13S condensin has a DNA-stimulated ATPase activity and exhibits a high affinity for structured DNAs such as cruciform DNA. 13S condensin is able to introduce positive supercoils into a closed circular DNA in the presence of bacterial or eukaryotic topoisomerase I. The supercoiling reaction is ATP-dependent. We propose that 13S condensin wraps DNA in a right-handed direction by utilizing the energy of ATP hydrolysis. This reaction may represent a key mechanism underlying the compaction of chromatin fibers during mitosis.

摘要

13S凝缩蛋白是一种由五个亚基组成的蛋白质复合体，在非洲爪蟾卵提取物的有丝分裂染色体凝聚过程中发挥核心作用。该复合体的两个核心亚基XCAP-C和XCAP-E属于一个新出现的假定ATP酶家族，即SMC家族。我们在此报告，13S凝缩蛋白具有DNA刺激的ATP酶活性，并且对诸如十字形DNA等结构化DNA表现出高亲和力。在细菌或真核拓扑异构酶I存在的情况下，13S凝缩蛋白能够将正超螺旋引入闭环DNA。超螺旋反应是ATP依赖性的。我们提出，13S凝缩蛋白通过利用ATP水解的能量以右手方向缠绕DNA。该反应可能代表有丝分裂期间染色质纤维压缩的关键机制。