DNA topoisomerase I from calf thymus mitochondria is associated with a DNA binding, inner membrane protein.
DNA topoisomerase I from calf thymus mitochondria is associated with a DNA binding, inner membrane protein.
复制标题
来自小牛胸腺线粒体的 DNA 拓扑异构酶 I 与 DNA 结合内膜蛋白相关。
DOI：
10.1016/0003-9861(92)90385-a
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发表时间：
1992
影响因子：
3.9
通讯作者：
Castora,FJ
中科院分区：
文献类型：
--
作者：
Lin,JH;Lazarus,GM;Castora,FJ
在从小牛胸腺线粒体纯化I型DNA拓扑异构酶的过程中，两种多肽p78和p63与酶活性一致（Lazaruset al.，（1987）Biochemistry 26，6195-6203）。这两种多肽通过非离子去污剂裂解从线粒体内膜制备物中释放，并且都强烈吸附到单链DNA琼脂糖柱上。我们试图表征这两种多肽之间的关系，并发现以下几点：（i）线粒体拓扑异构酶在游离（单体）和相关的（ii）催化活性仅存在于p78中，如通过酶与底物DNA的共价连接和酶松弛超螺旋的能力所判定的;（iii）在低离子强度下，所述酶以单体形式具有活性，单独的p78足以具有活性;（iv）在高盐下，所述高分子量物质是由一个p78和一个p63组成的140-kDa异二聚体;和（v）这两种多肽在结构上不相关，因为用V8蛋白酶消化产生不同的蛋白水解片段模式。这些结果表明，p63可能在线粒体拓扑异构酶的代谢中起重要作用。
During purification of the type I DNA topoisomerase from calf thymus mitochondria, two polypeptides, p78 and p63, cofractionate with the enzymatic activity (Lazaruset al., (1987) Biochemistry 26, 6195–6203). The two polypeptides are released from a mitochondrial inner membrane preparation by nonionic detergent lysis and both adsorb strongly to a single-stranded DNA agarose column. We have attempted to characterize the relationship between these two polypeptides and have found the following: (i) the mitochondrial topoisomerase is active in free (monomer) and associated (heterodimer) form; (ii) the catalytic activity resides solely in p78, as adjudged by both the covalent linkage of the enzyme to substrate DNA and the ability of the enzyme to relax supercoils; (iii) at low ionic strength the enzyme is active in monomer form with p78 alone being sufficient for activity; (iv) in high salt, the high molecular weight species is a 140-kDa heterodimer composed of one p78 and one p63; and (v) the two polypeptides are not structurally related as digestion with V8protease results in distinct proteolytic fragment patterns. These results suggest that p63 may have an important role in the metabolism of the mitochondrial topoisomerase.