Abstract

Glyoxalase I (GLO1) is a dimeric esterase of the glyoxalase system. Phosphorylation of the residue T106 has been found to inhibit GLO1 activity, and contribute to the onset of oxidative stress and cellular damage. This research uses multiple molecular dynamics simulations and automated docking of both GLO1 and dimerically phosphorylated GLO1 (p2-GLO1) to predict the initial structural differences induced by phosphorylation, and their interaction with the intermediate substrate Hemimercaptal. This research indicates that immediately following phosphorylation, GLO1 exhibits reduced sphericity, partly caused by outward splaying of the loop region surrounding T106. Phosphorylation induces enhanced concerted motions in the loop composed of residues immediately surrounding T106, which are correlated with motions at the active site pocket at the distant, opposite end of the dimer. These T106 region loop motions result in the distortion of the shape of the active site, and potentially alter its accessibility. Phosphorylation alters the manner in which GLO1 interacts with Hemimercaptal. For GLO1, Hemimercaptal is predicted to bind to T106, which we propose constitutes a novel, highly accessible ‘capture site’ responsible for initial contact with the substrate. In contrast, for p2-GLO1, Hemimercaptal is unable to bind favourably to (phosphorylated) position T106, suggesting that this proposed transient ‘capture site’ is abolished upon phosphorylation of GLO1. Hence, a novel physiological role is here proposed for the known essential GLO1 residue T106. These results may further contribute to understanding the inhibition mechanism of GLO1 upon phosphorylation.

Communicated by Ramaswamy H. Sarma

摘要

乙二醛酶 I (GLO1) 是乙二醛酶系统的二聚酯酶。已发现残基 T106 的磷酸化可抑制 GLO1 活性，并导致氧化应激和细胞损伤的发生。本研究使用 GLO1 和二聚体磷酸化 GLO1 (p2-GLO1) 的多重分子动力学模拟和自动对接来预测磷酸化诱导的初始结构差异，以及它们与中间底物 Hemimercaptal 的相互作用。这项研究表明，在磷酸化后，GLO1 的球形度立即降低，部分原因是 T106 周围的环区域向外张开。磷酸化在由紧邻 T106 周围的残基组成的环中诱导增强的协同运动，这与远处活性位点口袋的运动相关，二聚体的另一端。这些 T106 区域循环运动会导致活动位点的形状变形，并可能改变其可访问性。磷酸化改变了 GLO1 与 Hemimercaptal 相互作用的方式。对于 GLO1，Hemimercaptal 预计会与 T106 结合，我们建议它构成一个新颖的、高度可访问的“捕获位点”，负责与底物的初始接触。相比之下，对于 p2-GLO1，Hemimercaptal 不能有利地结合到（磷酸化的）位置 T106，这表明该提议的瞬时“捕获位点”在 GLO1 磷酸化后被消除。因此，这里为已知的必需 GLO1 残基 T106 提出了一种新的生理作用。这些结果可能进一步有助于理解 GLO1 对磷酸化的抑制机制。这些 T106 区域循环运动会导致活动位点的形状变形，并可能改变其可访问性。磷酸化改变了 GLO1 与 Hemimercaptal 相互作用的方式。对于 GLO1，Hemimercaptal 预计会与 T106 结合，我们建议它构成一个新颖的、高度可访问的“捕获位点”，负责与底物的初始接触。相比之下，对于 p2-GLO1，Hemimercaptal 不能有利地结合到（磷酸化的）位置 T106，这表明该提议的瞬时“捕获位点”在 GLO1 磷酸化后被消除。因此，这里为已知的必需 GLO1 残基 T106 提出了一种新的生理作用。这些结果可能进一步有助于理解 GLO1 对磷酸化的抑制机制。这些 T106 区域循环运动会导致活动位点的形状变形，并可能改变其可访问性。磷酸化改变了 GLO1 与 Hemimercaptal 相互作用的方式。对于 GLO1，Hemimercaptal 预计会与 T106 结合，我们建议它构成一个新颖的、高度可访问的“捕获位点”，负责与底物的初始接触。相比之下，对于 p2-GLO1，Hemimercaptal 不能有利地结合到（磷酸化的）位置 T106，这表明该提议的瞬时“捕获位点”在 GLO1 磷酸化后被消除。因此，这里为已知的必需 GLO1 残基 T106 提出了一种新的生理作用。这些结果可能进一步有助于理解 GLO1 对磷酸化的抑制机制。

由 Ramaswamy H. Sarma 传达