Biology Faculty, Lomonosov Moscow State University, Moscow, 119992, Russia.
Institute of Physics and Mathematics, Astrakhan State University, Astrakhan, 414056, Russia.
Physiol Plant. 2019 May;166(1):320-335. doi: 10.1111/ppl.12940. Epub 2019 Mar 27.
Mechanisms of the complex formation between plastocyanin and cytochrome f in higher plants (Spinacia oleracea and Brassica rapa), green microalgae Chlamydomonas reinhardtii and two species of cyanobacteria (Phormidium laminosum and Nostoc sp.) were investigated using combined Brownian and molecular dynamics simulations and hierarchical cluster analysis. In higher plants and green algae, electrostatic interactions force plastocyanin molecule close to the heme of cytochrome f. In the subsequent rotation of plastocyanin molecule around the point of electrostatic contact in the vicinity of cytochrome f, copper (Cu) atom approaches cytochrome heme forming a stable configuration where cytochrome f molecule behaves as a rather rigid body without conformational changes. In Nostoc plastocyanin molecule approaches cytochrome f in a different orientation (head-on) where the stabilization of the plastocyanin-cytochrome f complex is accompanied by the conformational changes of the G188E189D190 loop that stabilizes the whole complex. In cyanobacterium P. laminosum, electrostatic preorientation of the approaching molecules was not detected, thus indicating that random motions rather than long-range electrostatic interactions are responsible for the proper mutual orientation. We demonstrated that despite the structural similarity of the investigated electron transport proteins in different photosynthetic organisms, the complexity of molecular mechanisms of the complex formation increases in the following sequence: non-heterocystous cyanobacteria - heterocystous cyanobacteria - green algae - flowering plants.
采用布朗动力学和分子动力学模拟结合层级聚类分析的方法，研究了高等植物（菠菜和油菜）、绿藻（莱茵衣藻）以及两种蓝藻（平裂藻和念珠藻）中质体蓝蛋白与细胞色素 f 形成复合物的机制。在高等植物和绿藻中，静电相互作用促使质体蓝蛋白分子靠近细胞色素 f 的血红素。在随后的质体蓝蛋白分子绕着细胞色素 f 附近静电接触点的旋转过程中，铜（Cu）原子接近细胞色素血红素，形成一个稳定的构型，其中细胞色素 f 分子表现为一个相当刚性的体，没有构象变化。在念珠藻中，质体蓝蛋白分子以不同的取向（迎头）接近细胞色素 f，其中质体蓝蛋白-细胞色素 f 复合物的稳定伴随着 G188E189D190 环的构象变化，该环稳定了整个复合物。在蓝藻平裂藻中，没有检测到接近分子的静电预定向，这表明是随机运动而不是长程静电相互作用负责适当的相互取向。我们证明，尽管不同光合生物中被研究的电子传递蛋白在结构上具有相似性，但复合物形成的分子机制的复杂性按以下顺序增加：非异形胞蓝藻-异形胞蓝藻-绿藻-开花植物。
