Physik Department E22, Technische Universität München, 85748 Garching, Germany.
Department of Chemistry, University of Cincinnati, Cincinnati, OH 45221.
Proc Natl Acad Sci U S A. 2017 Jun 6;114(23):6040-6045. doi: 10.1073/pnas.1619843114. Epub 2017 May 22.
Owing to the cooperativity of protein structures, it is often almost impossible to identify independent subunits, flexible regions, or hinges simply by visual inspection of static snapshots. Here, we use single-molecule force experiments and simulations to apply tension across the substrate binding domain (SBD) of heat shock protein 70 (Hsp70) to pinpoint mechanical units and flexible hinges. The SBD consists of two nanomechanical units matching 3D structural parts, called the α- and β-subdomain. We identified a flexible region within the rigid β-subdomain that gives way under load, thus opening up the α/β interface. In exactly this region, structural changes occur in the ATP-induced opening of Hsp70 to allow substrate exchange. Our results show that the SBD's ability to undergo large conformational changes is already encoded by passive mechanics of the individual elements.
由于蛋白质结构的协同性，仅通过静态快照的直观检查，几乎不可能识别独立的亚基、柔性区域或铰链。在这里，我们使用单分子力实验和模拟在热休克蛋白 70（Hsp70）的底物结合域（SBD）上施加张力，以确定机械单元和柔性铰链。SBD 由两个纳米力学单元组成，与 3D 结构部分匹配，称为α-和β-结构域。我们在刚性β-结构域内识别出一个在负载下让路的柔性区域，从而打开α/β 界面。在 Hsp70 的 ATP 诱导打开以允许底物交换的 exactly 这个区域，发生结构变化。我们的结果表明，SBD 进行大构象变化的能力已经由单个元素的被动力学编码。
