Nano Biotechnology Center, Marky Cancer Center, and College of Pharmacy, University of Kentucky, Lexington, KY 40536, USA.
Nano Biotechnology Center, Marky Cancer Center, and College of Pharmacy, University of Kentucky, Lexington, KY 40536, USA.
Biotechnol Adv. 2014 Jul-Aug;32(4):853-72. doi: 10.1016/j.biotechadv.2014.01.006.
Biomotors were once described into two categories: linear motor and rotation motor. Recently, a third type of biomotor with revolution mechanism without rotation has been discovered. By analogy, rotation resembles the Earth rotating on its axis in a complete cycle every 24h, while revolution resembles the Earth revolving around the Sun one circle per 365 days (see animations http://nanobio.uky.edu/movie.html). The action of revolution that enables a motor free of coiling and torque has solved many puzzles and debates that have occurred throughout the history of viral DNA packaging motor studies. It also settles the discrepancies concerning the structure, stoichiometry, and functioning of DNA translocation motors. This review uses bacteriophages Phi29, HK97, SPP1, P22, T4, and T7 as well as bacterial DNA translocase FtsK and SpoIIIE or the large eukaryotic dsDNA viruses such as mimivirus and vaccinia virus as examples to elucidate the puzzles. These motors use ATPase, some of which have been confirmed to be a hexamer, to revolve around the dsDNA sequentially. ATP binding induces conformational change and possibly an entropy alteration in ATPase to a high affinity toward dsDNA; but ATP hydrolysis triggers another entropic and conformational change in ATPase to a low affinity for DNA, by which dsDNA is pushed toward an adjacent ATPase subunit. The rotation and revolution mechanisms can be distinguished by the size of channel: the channels of rotation motors are equal to or smaller than 2 nm, that is the size of dsDNA, whereas channels of revolution motors are larger than 3 nm. Rotation motors use parallel threads to operate with a right-handed channel, while revolution motors use a left-handed channel to drive the right-handed DNA in an anti-chiral arrangement. Coordination of several vector factors in the same direction makes viral DNA-packaging motors unusually powerful and effective. Revolution mechanism that avoids DNA coiling in translocating the lengthy genomic dsDNA helix could be advantageous for cell replication such as bacterial binary fission and cell mitosis without the need for topoisomerase or helicase to consume additional energy.
线性马达和旋转马达。最近，人们发现了第三种具有旋转机制而无旋转的生物马达。类比来说，旋转类似于地球每 24 小时绕其轴完整旋转一周，而旋转类似于地球每 365 天绕太阳旋转一圈（参见动画 http://nanobio.uky.edu/movie.html）。这种旋转机制的运动使得无绕组和转矩的马达得以实现，解决了病毒 DNA 包装马达研究历史上出现的许多谜题和争议。它还解决了 DNA 转位马达的结构、化学计量和功能的差异。本综述使用噬菌体 Phi29、HK97、SPP1、P22、T4 和 T7 以及细菌 DNA 转位酶 FtsK 和 SpoIIIE 或大型真核双链 DNA 病毒（如 mimivirus 和痘病毒）作为例子来阐明这些谜题。这些马达使用 ATP 酶，其中一些已被证实为六聚体，依次围绕 dsDNA 旋转。ATP 结合诱导 ATP 酶构象变化和可能的熵变，使其对 dsDNA 具有高亲和力；但 ATP 水解会导致 ATP 酶发生另一种熵变和构象变化，使其对 DNA 的亲和力降低，从而将 dsDNA 推向相邻的 ATP 酶亚基。旋转和旋转机制可以通过通道的大小来区分：旋转马达的通道等于或小于 2nm，即 dsDNA 的大小，而旋转马达的通道大于 3nm。旋转马达使用平行线程以右手通道运行，而旋转马达使用左手通道以反手排列驱动右手 DNA。同一方向上的几个向量因子的协调使得病毒 DNA 包装马达非常强大和有效。在转移长基因组 dsDNA 螺旋时避免 DNA 缠绕的旋转机制可能有利于细胞复制，例如细菌二分分裂和细胞有丝分裂，而不需要拓扑异构酶或解旋酶消耗额外的能量。
