Lehrstuhl für Biophysik E27, Technische Universität München, Garching, Germany.
Cell Rep. 2012 Sep 27;2(3):433-9. doi: 10.1016/j.celrep.2012.08.014. Epub 2012 Sep 20.
The local interaction of F-actin with myosin-II motor filaments and crosslinking proteins is crucial for the force generation, dynamics, and reorganization of the intracellular cytoskeleton. By using a bottom-up approach, we are able to show that the contractility of reconstituted active actin systems is tightly controlled by the local pH. The pH-dependent intrinsic crossbridge strength of myosin-II is identified to account for a sharp transition of the actin/myosin-II activity from noncontractile to contractile by a change in pH of only 0.1. This pH-dependent contractility is a generic feature, which is observed in all studied crosslinked actin/myosin-II systems. The specific type and concentration of crosslinking protein allows one to sensitively adjust the range of pH where contraction occurs, which can recover the behavior found in Xenopus laevis oocyte extracts. Small variations in pH provide a mechanism of controlling the contractility of cytoskeletal structures, which can be expected to have broad implications in our understanding of cytoskeletal regulation.
肌动球蛋白与交联蛋白的局部相互作用对于细胞内细胞骨架的力产生、动力学和重排至关重要。通过采用自下而上的方法，我们能够表明，重组活性肌动蛋白系统的收缩性受到局部 pH 值的严格控制。发现肌球蛋白 II 的 pH 依赖性固有交联桥强度可以解释通过仅改变 0.1 的 pH 值，肌动球蛋白/肌球蛋白 II 的活性从非收缩性到收缩性的急剧转变。这种 pH 依赖性收缩性是一种普遍特征，在所有研究的交联肌动球蛋白/肌球蛋白 II 系统中都观察到。交联蛋白的特定类型和浓度允许人们敏感地调整收缩发生的 pH 范围，这可以恢复在非洲爪蟾卵母细胞提取物中发现的行为。pH 的微小变化提供了一种控制细胞骨架结构收缩性的机制，这有望对我们理解细胞骨架调节产生广泛影响。
