Institute of Physics, Carl von Ossietzky University of Oldenburg, Carl-von-Ossietzky Straße 9-11, Oldenburg 26129, Germany.
Graduate School of Science and Engineering, Saitama University, 255 Shimo-okubo, Sakura Ward, Saitama 338-8570, Japan.
J Phys Chem B. 2023 Jul 20;127(28):6251-6264. doi: 10.1021/acs.jpcb.3c01305. Epub 2023 Jul 10.
Homo-dimer formation is important for the function of many proteins. Although dimeric forms of cryptochromes (Cry) have been found by crystallography and were recently observed in vitro for European robin Cry4a, little is known about the dimerization of avian Crys and the role it could play in the mechanism of magnetic sensing in migratory birds. Here, we present a combined experimental and computational investigation of the dimerization of robin Cry4a resulting from covalent and non-covalent interactions. Experimental studies using native mass spectrometry, mass spectrometric analysis of disulfide bonds, chemical cross-linking, and photometric measurements show that disulfide-linked dimers are routinely formed, that their formation is promoted by exposure to blue light, and that the most likely cysteines are C317 and C412. Computational modeling and molecular dynamics simulations were used to generate and assess a number of possible dimer structures. The relevance of these findings to the proposed role of Cry4a in avian magnetoreception is discussed.
同源二聚体的形成对于许多蛋白质的功能很重要。尽管晶体学已经发现了隐花色素（Cry）的二聚体形式，并且最近在欧洲知更鸟 Cry4a 的体外观察到了这种形式，但关于鸟类 Crys 的二聚化及其在候鸟磁感觉机制中可能发挥的作用知之甚少。在这里，我们结合实验和计算研究了罗宾 Cry4a 的二聚化，这种二聚化是由共价和非共价相互作用引起的。使用天然质谱、二硫键质谱分析、化学交联和光度测量的实验研究表明，二硫键连接的二聚体通常会形成，它们的形成会受到蓝光的促进，最有可能的半胱氨酸是 C317 和 C412。计算建模和分子动力学模拟被用来生成和评估许多可能的二聚体结构。讨论了这些发现与 Cry4a 在鸟类磁感觉中提出的作用的相关性。
