An ATP hydrolysis sensor in the DNA packaging motor from bacteriophage T4 suggests an inchworm-type translocation mechanism
An ATP hydrolysis sensor in the DNA packaging motor from bacteriophage T4 suggests an inchworm-type translocation mechanism
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DOI：
10.1016/j.jmb.2007.03.019
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发表时间：
2007-05-25
影响因子：
5.6
通讯作者：
Rao, Venigalla B.
中科院分区：
文献类型：
--
作者：
Draper, Bonnie;Rao, Venigalla B.
尾状噬菌体和大型真核病毒利用强大的分子马达将dsDNA转移到预组装的衣壳中。噬菌体T4马达由十二体门体和大小端酶亚基组成，这些亚基组装在前体的特殊头尾接头顶点。马达利用存在于大端酶亚基中的ATP酶提供的ATP水解能量，将DNA泵入门脉通道。我们报道了末端酶、解旋酶、易位限制性内切酶和蛋白质转位酶的atp酶马达具有一个共同的偶联基序（c -基序）。噬菌体T4端酶c基序的突变导致受刺激的atp酶和DNA易位活性的丧失。令人惊讶的是，突变体可以催化至少一个ATP水解事件，但不能翻转和重置马达。这是首次报道ATP水解发生后ATP酶马达易位的催化阻滞。我们认为c基序是ATP水解传感器，将产物释放与机械运动联系起来。提出了一种新的末端驱动的病毒dsDNA易位机制。(c) 2007 Elsevier Ltd.版权所有。
Tailed bacteriophages and large eukaryotic viruses employ powerful molecular motors to translocate dsDNA into a preassembled capsid shell. The phage T4 motor is composed of a dodecameric portal and small and large terminase subunits assembled at the special head-tail connector vertex of the prohead. The motor pumps DNA through the portal channel, utilizing ATP hydrolysis energy provided by an ATPase present in the large terminase subunit. We report that the ATPase motors of terminases, helicases translocating restriction enzymes, and protein translocases possess a common coupling motif (C-motif). Mutations in the phage T4 terminase C-motif lead to loss of stimulated ATPase and DNA translocation activities. Surprisingly, the mutants can catalyze at least one ATP hydrolysis event but are unable to turn over and reset the motor. This is the first report of a catalytic block in translocating ATPase motor after ATP hydrolysis occurred. We suggest that the C-motif is an ATP hydrolysis sensor, linking product release to mechanical motion. A novel terminase-driven mechanism is proposed for translocation of dsDNA in viruses. (c) 2007 Elsevier Ltd. All rights reserved.