Kinetic mechanism of DNA unwinding by the BLM helicase core and molecular basis for its low processivity.
Kinetic mechanism of DNA unwinding by the BLM helicase core and molecular basis for its low processivity.
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DOI：
10.1021/bi901459c
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发表时间：
2010-01
期刊：
影响因子：
2.9
通讯作者：
Ye Yang;Shuoxing Dou;Ya-Nan Xu;Nicolas Bazeille;Peng-Ye Wang;P. Rigolet;Hou-Qiang Xu;X. Xi
中科院分区：
文献类型：
--
作者：
Ye Yang;Shuoxing Dou;Ya-Nan Xu;Nicolas Bazeille;Peng-Ye Wang;P. Rigolet;Hou-Qiang Xu;X. Xi
布卢姆综合征（BS）是一种罕见的人类常染色体隐性遗传疾病，其特征是对广泛的癌症具有强烈的易感性，通常影响普通人群。了解BLM蛋白的功能机制可能为开发新的有效治疗策略提供机会。在这项工作中，我们研究了DNA解旋动力学机制的解旋酶核心的BLM蛋白质使用各种停流分析。我们表明，解旋酶核心的BLM解旋双链DNA作为单体，即使在条件下强烈有利于寡聚化。解旋速率约为每秒20步，步长为1 bp。我们已经观察到解旋酶具有非常低的持续合成能力。从解离和抑制实验中，我们发现，在DNA解旋的ATP水解周期中，解旋酶倾向于从ADP状态的DNA底物解离。实验结果表明，BLM解旋酶核心可以以尺蠖的方式解旋双链体DNA。
Bloom's syndrome (BS) is a rare human autosomal recessive disorder characterized by a strong predisposition to a wide range of cancers commonly affecting the general population. Understanding the functioning mechanism of the BLM protein may provide the opportunity to develop new effective therapy strategies. In this work, we studied the DNA unwinding kinetic mechanism of the helicase core of the BLM protein using various stopped-flow assays. We show that the helicase core of BLM unwinds duplex DNA as monomers even under conditions strongly favoring oligomerization. An unwinding rate of approximately 20 steps per second and a step size of 1 bp have been determined. We have observed that the helicase has a very low processivity. From dissociation and inhibition experiments, we have found that during its ATP hydrolysis cycle in DNA unwinding the helicase tends to dissociate from the DNA substrate in the ADP state. The experimental results imply that the BLM helicase core may unwind duplex DNA in an inchworm manner.