T4病毒的DNA需要在特定分子马达的帮助下，才能进入病毒的蛋白壳内。Purdue大学和美国Catholic大学的研究人员最近发现了一种在此机制中扮演重要角色的酶：三磷酸腺苷酶（ATPase）的结构。这篇文章第一作者为Purdue大学科学院Michael Rossmann实验室博士后研究员Siyang Sun。研究内容刊载3月22日的Molecular Cell中。
这种分子马达在其它病毒中也存在，包括人类疱疹病毒。病毒首先组装蛋白头部的蛋白壳，然后将DNA装入空的衣壳中。这种过程可以比喻为建造房屋，然后添加家具。
DNA记录了病毒的全部特征，衣壳保护了这种记录，确保病毒能够通过感染宿主不断繁殖。ATPase将ATP降解为ADP时，产生包装所需的能量。ATPase可破坏磷酸盐和ADP之间的化学键。
研究人员将运转T4病毒的分子马达所需的ATPase结构，与解旋酶（helicases）的结构进行比对，推测出一种可能的马达运作机制。
解旋酶是在基因复制过程中将双链DNA分开为单链的酶。DNA复制过程中，解旋酶会选择性结合或脱离DNA，沿着螺旋移动将双链分为单链。研究人员推测病毒的分子马达，也是利用相似的机制将DNA挤入病毒中。
研究人员利用X射线结晶学技术分析了ATPase的结构。这项研究结果有助于设计出可干扰这些病毒分子马达的药物，以治疗病毒感染、发展微型的纳米马达。
(资料来源 : Bio.com)
部分英文原文：
Molecular Cell, Vol 25, 943-949, 23 March 2007
Short Article
The Structure of the ATPase that Powers DNA Packaging into Bacteriophage T4 Procapsids
Siyang Sun,1 Kiran Kondabagil,2 Petra M. Gentz,1,3 Michael G. Rossmann,1, and Venigalla B. Rao2,
1 Department of Biological Sciences, Purdue University, 915 W. State Street, West Lafayette, IN 47907, USA
2 Department of Biology, The Catholic University of America, 620 Michigan Avenue NE, Washington, DC 20064, USA
Corresponding author
Michael G. Rossmann
mr@purdue.edu
Corresponding author
Venigalla B. Rao
rao@cua.edu
Summary
Packaging the viral genome into empty procapsids, an essential event in the life cycle of tailed bacteriophages and some eukaryotic viruses, is a process that shares features with chromosome assembly. Most viral procapsids possess a special vertex containing a dodecameric portal protein that is used for entry and exit of the viral genome. The portal and an ATPase are parts of the genome-packaging machine. The ATPase is required to provide energy for translocation and compaction of the negative charges on the genomic DNA. Here we report the atomic structure of the ATPase component in a phage DNA-packaging machine. The bacteriophage T4 ATPase has the greatest similarity to monomeric helicases, suggesting that the genome is translocated by an inchworm mechanism. The similarity of the packaging machines in the double-stranded DNA (dsDNA) bacteriophage T4 and dsRNA bacteriophage 12 is consistent with the evolution of many virions from a common ancestor.
英文全文链接：http://www.molecule.org/content/article/fulltext?uid=PIIS109727650700113X
