Xue Xiaoyu, Choi Koyi, Bonner Jacob N, Chiba Tamara, Kwon Youngho, Xu Yuanyuan, Sanchez Humberto, Wyman Claire, Niu Hengyao, Zhao Xiaolan, Sung Patrick
Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, CT 06520, USA.
Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA; Programs in Biochemistry, Cell, and Molecular Biology, Weill Graduate School of Medical Sciences of Cornell University, New York, NY 10021, USA.
Mol Cell. 2014 Nov 6;56(3):436-445. doi: 10.1016/j.molcel.2014.09.013. Epub 2014 Oct 16.
Conserved, multitasking DNA helicases mediate diverse DNA transactions and are relevant for human disease pathogenesis. These helicases and their regulation help maintain genome stability during DNA replication and repair. We show that the structural maintenance of chromosome complex Smc5-Smc6 restrains the replication fork regression activity of Mph1 helicase, but not its D loop disruptive activity. This regulatory mechanism enables flexibility in replication fork repair without interfering with DNA break repair. In vitro studies find that Smc5-Smc6 binds to a Mph1 region required for efficient fork regression, preventing assembly of Mph1 oligomers at the junction of DNA forks. In vivo impairment of this regulatory mechanism compensates for the inactivation of another fork regression helicase and increases reliance on joint DNA structure removal or avoidance. Our findings provide molecular insights into replication fork repair regulation and uncover a role of Smc5-Smc6 in directing Mph1 activity toward a specific biochemical outcome.
保守的多功能DNA解旋酶介导多种DNA事务，与人类疾病发病机制相关。这些解旋酶及其调控有助于在DNA复制和修复过程中维持基因组稳定性。我们发现，染色体结构维持复合体Smc5-Smc6抑制Mph1解旋酶的复制叉回归活性，但不抑制其D环破坏活性。这种调控机制使复制叉修复具有灵活性，而不会干扰DNA断裂修复。体外研究发现，Smc5-Smc6与有效叉回归所需的Mph1区域结合，阻止Mph1寡聚体在DNA叉的交界处组装。体内这种调控机制的损伤补偿了另一种叉回归解旋酶的失活，并增加了对联合DNA结构去除或避免的依赖。我们的研究结果为复制叉修复调控提供了分子见解，并揭示了Smc5-Smc6在引导Mph1活性实现特定生化结果中的作用。
