固有无序超嗜热菌FlgM蛋白在两种不同温度下的构象变化特征

摘要

The aim of this work was to compare the structural characteristics of the FlgM protein from the thermophile aquifex aeolicus at room temperature (293 K) and at the physiological temperature (358 K) using molecular dynamics simulations. Two independent long-time molecular dynamics simulations were performed using the GROMACS software package at 293 and 358 K, respectively. The OPLS-AA force field and the TIP3P water model were used. Each simulation was run for 1500 ns. We mainly analyzed the secondary structural characteristics, the overal conformation variation, the conformational characteristics of a semi-disordered region and the structured region of the FlgM protein at two different temperatures. The results indicate that the helix structure of the N terminal increased at room temperature. The FlgM protein had the fol owing characteristics at the physiological temperature:the structure loosed, the helix structure reduced in size, the conformational stability weakened, the H1 helix spread, the conformational flexibility increased, and the degree of instability increased. In summary, the semi-disordered region (N terminal) formed a helical structure in the unbound state and its stability decreased with an increase in temperature. The FlgM protein adapts to temperature by increasing the degree of disorder, creating a more flexible structure by improving the binding rate.%基于分子动力学模拟方法比较了超嗜热菌FlgM蛋白在常温(293 K)和生理温度(358 K)下的结构特征.基于GROMACS软件包,采用OPLS-AA分子力场和TIP3P水模型,对超嗜热菌FlgM蛋白在293和358 K进行了2组独立的长时间分子动力学模拟,每组体系模拟时间为1500 ns.主要分析了两种温度下超嗜热菌FlgM蛋白的二级结构特征、整体构象变化及半无序化区域和结构化区域的构象特征.研究结果表明：在常温下,N端具有一定程度的螺旋成分,但在生理温度下,超嗜热菌FlgM蛋白的结构变得松散,螺旋结构减少,构象稳定性减弱, H1螺旋散开, FlgM蛋白构象灵活性增强,不稳定程度增加.这些不同温度的结构变化说明：半无序化区域(N端)在非结合状态下有一定的螺旋结构,但该段螺旋的稳定性随温度升高而降低.超嗜热菌FlgM蛋白会通过增加结构的无序程度使结构更加灵活,以适应高温,从而使该类固有无序蛋白更好地行使其功能,如提高同其他成分的结合速率等.