Richard Janissen, Roman Barth, Iain F. Davidson, Jan-Michael Peters, Cees Dekker
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引用次数: 0
Abstract
Eukaryotes carry three types of structural maintenance of chromosome (SMC) protein complexes, condensin, cohesin, and SMC5/6, which are ATP-dependent motor proteins that remodel the genome via DNA loop extrusion (LE). SMCs modulate DNA supercoiling but remains incompletely understood how this is achieved. Using a single-molecule magnetic tweezers assay that directly measures how much twist is induced by individual SMCs in each LE step, we demonstrate that all three SMC complexes induce the same large negative twist (i.e., linking number change ΔLk of ~−0.6 at each LE step) into the extruded loop, independent of step size and DNA tension. Using ATP hydrolysis mutants and nonhydrolyzable ATP analogs, we find that ATP binding is the twist-inducing event during the ATPase cycle, coinciding with the force-generating LE step. The fact that all three eukaryotic SMC proteins induce the same amount of twist indicates a common DNA-LE mechanism among these SMC complexes.
真核生物携带三种类型的染色体结构维护(SMC)蛋白复合物,即凝集素、粘合素和 SMC5/6,它们是依赖 ATP 的运动蛋白,通过 DNA 环挤压(LE)重塑基因组。SMC 可调节 DNA 的超卷曲,但人们对其实现方式仍不甚了解。我们利用单分子磁镊检测法直接测量了单个 SMC 在每个 LE 步骤中诱导的扭曲程度,结果表明所有三种 SMC 复合物都会诱导挤出环产生相同的大负向扭曲(即在每个 LE 步骤中链接数变化 Δ L k 为 ~-0.6),这与步骤大小和 DNA 张力无关。利用 ATP 水解突变体和非水解 ATP 类似物,我们发现 ATP 结合是 ATP 酶周期中的扭转诱导事件,与产生力的 LE 步骤相吻合。所有三种真核生物 SMC 蛋白都能诱导相同数量的扭转,这一事实表明这些 SMC 复合物具有共同的 DNA-LE 机制。
期刊介绍:
Science Advances, an open-access journal by AAAS, publishes impactful research in diverse scientific areas. It aims for fair, fast, and expert peer review, providing freely accessible research to readers. Led by distinguished scientists, the journal supports AAAS's mission by extending Science magazine's capacity to identify and promote significant advances. Evolving digital publishing technologies play a crucial role in advancing AAAS's global mission for science communication and benefitting humankind.