Archaeal Hel308 domain V couples DNA binding to ATP hydrolysis and positions DNA for unwinding over the helicase ratchet.
Archaeal Hel308 domain V couples DNA binding to ATP hydrolysis and positions DNA for unwinding over the helicase ratchet.
复制标题
DOI：
10.1016/j.jmb.2007.10.004
复制
发表时间：
2007-12
影响因子：
5.6
通讯作者：
Isabel L Woodman;G. S. Briggs;E. Bolt
中科院分区：
文献类型：
--
作者：
Isabel L Woodman;G. S. Briggs;E. Bolt
Hel308 和 PolQ 是旁系同源物，具有促进古细菌和高等真核生物基因组稳定性的作用。尽管来自古细菌的 Hel308 解旋酶可能与异常复制叉相互作用，但它们的作用背景尚不清楚。最近报道了来自古生球菌的古菌 Hel308 与 DNA 复合物的原子结构，并为超家族 2 解旋酶的一般机制提供了见解。该结构的一个有趣的方面是 C 端结构域 V 相对于单链 DNA 和解旋酶棘轮结构域 IV 的定位。我们对古细菌 Hel308 的结构域 V 中的精氨酸残基三联体进行了诱变，以评估对 DNA 结合、解旋和 ATP 酶活性的影响。现在可以根据原子结构来解释我们的观察结果。我们描述了结构域 V 作为 ATP 水解制动器的关键作用，通过将其与结合单链 DNA 偶联，并将 DNA 相对于解旋酶棘轮结构域 IV 定位，以有效解开分叉 DNA。
Hel308 and PolQ are paralogues with roles promoting genome stability in archaea and higher eukaryotes. The context in which they act is not clear, although Hel308 helicase from archaea may interact with abnormal replication forks. The atomic structure of archaeal Hel308 from Archaeoglobus fulgidus in complex with DNA was recently reported and has given insights into the mechanisms of superfamily-2 helicases generally. An intriguing aspect of the structure was the positioning of a C-terminal domain V relative to single-stranded DNA and to the helicase ratchet domain IV. We have mutagenised a triplet of arginine residues in domain V of archaeal Hel308 to assess the effects on DNA binding, unwinding, and ATPase activities. Our observations can now be interpreted in light of the atomic structure. We describe crucial roles for domain V as a brake on ATP hydrolysis by coupling it to binding single-stranded DNA and in positioning DNA relative to the helicase ratchet domain IV for efficient unwinding of forked DNA.