Dipartimento di Scienze, Università degli Studi Roma Tre, Via della Vasca Navale 84, 00146 Roma, Italy; Institute of Crystallography, CNR, via Salaria, Km 29.300, 00015 Monterotondo, Roma, Italy; Rome International Center for Materials Science Superstripes (RICMASS), Via dei Sabelli 119A, 00185 Roma, Italy.
Institute of Crystallography, CNR, via Salaria, Km 29.300, 00015 Monterotondo, Roma, Italy; Rome International Center for Materials Science Superstripes (RICMASS), Via dei Sabelli 119A, 00185 Roma, Italy; National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), 115409 Moscow, Russia.
Biochim Biophys Acta Biomembr. 2020 Jun 1;1862(6):183256. doi: 10.1016/j.bbamem.2020.183256. Epub 2020 Mar 5.
Living matter is a quasi-stationary out-of-equilibrium system; in this physical condition, structural fluctuations at nano- and meso-scales are needed to understand the physics behind its biological functionality. Myelin has a simple ultrastructure whose fluctuations show correlated disorder in its functional out-of-equilibrium state. However, there is no information on the relationship between this correlated disorder and the dynamics of the intrinsically disordered Myelin Basic Protein (MBP) which is expected to influence the membrane structure and overall functionality. In this work, we have investigated the role of this protein structural dynamics in the myelin ultrastructure fluctuations in various conditions, by using synchrotron Scanning micro X Ray Diffraction and Small Angle X ray Scattering. We have induced the crossover from out-of-equilibrium functional state to in-equilibrium degeneration changing the pH to values far from physiological condition. The observed compression of the cytosolic layer thickness probes that the intrinsic large MBP fluctuations preserve the cytosol structure also in the degraded state. Thus, the transition of myelin ultrastructure from correlated to uncorrelated disordered state, is principally affected by the deformation of the membrane and extracellular domain.
生命物质是一种准静态的非平衡系统；在这种物理状态下，需要纳米和介观尺度的结构涨落来理解其生物功能背后的物理学。髓鞘具有简单的超微结构，其涨落显示出在其非平衡功能状态下的相关无序。然而，关于这种相关无序与预期会影响膜结构和整体功能的内在无序髓鞘碱性蛋白（MBP）的动力学之间的关系，目前还没有信息。在这项工作中，我们通过使用同步辐射扫描微 X 射线衍射和小角 X 射线散射，研究了这种蛋白质结构动力学在各种条件下对髓鞘超微结构涨落的作用。我们通过将 pH 值改变到远离生理条件的值，诱导了从非平衡功能状态到平衡退化状态的交叉。观察到胞质层厚度的压缩表明，内在的 MBP 大波动也在退化状态下保持了胞质结构。因此，髓鞘超微结构从相关无序到不相关无序状态的转变，主要受膜和细胞外域的变形影响。
