CLC氯通道蛋白的结构与功能关系的研究

发布时间：2018-06-28 22:39

本文选题：氯离子通道 + ClC-0　；参考：《武汉大学》2010年博士论文

【摘要】： ClC氯通道蛋白是一类重要的离子通道蛋白,它们广泛存在于原核细胞和真核细胞中,包括哺乳动物中。它具有重要的生理功能,当它的功能缺失时会引起许多疾病,如肌强直,不孕不育,耳聋等。它在细菌中的同源物的晶体结构在2002年被测得。在此之后一系列实验研究出现,但是实验只能得到通道的宏观性质,对于微观分子机制却很少涉及,因此从分子角度研究它的结构与功能的关系具有非常重要的意义。我们利用分子动力学,连续静电计算,建模等方法,研究了ClC氯通道的结构和功能特性,揭示其微观机制。 1.提出ClC-0氯离子通道导电性质的三态多离子输运模型我们提出了一个三态多离子输运模型,它能很好地解释氯离子通道ClC-0的导电特性。将速率理论用于此模型,得到电流-电压和电导率-浓度的关系。模型中的五个可调参数,是通过拟合野生型ClC-0和它的变异体K519C的实验数据得到的。作为检验,将这个模型得到的数据与采用其他计算和模拟方法得到的数据进行比较。结果表明,从这个模型计算出的不同氯离子占据态之间的能量差与通过解泊松-玻尔兹曼方程得到的结合自由能是一致的。从此模型得到的平均导电离子数和离子通过速率与实验上的结果也是一致的。根据这个模型,由于残基K519变异成C519产生的电导率的下降能被归结为K519C变异对各个态之间转换速率常数的影响。这个工作有助于人们理解ClC-0的导电机制。 2.研究ClC-ec1中残基变异对氯离子静电结合自由能的影响 ClC通道蛋白的残基变异导致蛋白功能的改变,引发许多疾病。现已查明,ClC蛋白功能的实现与氯离子在通道中的结合能密切相关。因此研究残基变异对ClC-ec1功能的影响可以通过研究残基变异对氯离子在通道中的结合能的影响来体现。我们系统地研究了各种残基变异对氯离子在通道中的结合能的影响。通过使用全原子分子动力学模拟和静电计算,揭示出残基变异引起的电荷变化和残基与氯离子结合位点的距离是影响氯离子结合能的重要因素。这一工作在分子层次上使人们认识了ClC通道蛋白的残基变异对蛋白功能影响的实质。
[Abstract]:CLC chloride channel proteins are important ion channel proteins which are widely distributed in prokaryotic cells and eukaryotic cells including mammals. It has important physiological functions. When its function is absent, it can cause many diseases, such as myotonia, infertility, deafness and so on. The crystal structure of its homologues in bacteria was measured in 2002. After this, a series of experimental studies appeared, but the experiment can only get the macroscopic properties of the channel, but it is seldom involved in the micro molecular mechanism. Therefore, it is very important to study the relationship between the structure and the function from the molecular point of view. By means of molecular dynamics, continuous electrostatic calculation and modeling, the structure and functional characteristics of chlorine channels of ClC have been studied, and the microscopic mechanism has been revealed. 1. A three-state multi-ion transport model for the conductivity of ClC-0 chloride channel is presented. A three-state multi-ion transport model is proposed, which can explain the conductivity of chloride channel ClC-0 well. Applying the rate theory to this model, the relationship between current-voltage and conductivity-concentration is obtained. The five adjustable parameters in the model are obtained by fitting the experimental data of wild type ClC-0 and its variant K519C. As a test, the data obtained by this model are compared with those obtained by other calculation and simulation methods. The results show that the energy difference between the different chloride ion occupied states calculated from this model is consistent with the binding free energy obtained by solving Poisson Boltzmann equation. The average number of conducting ions and the ion passing rate obtained from the model are in agreement with the experimental results. According to this model, the decrease of conductivity due to the mutation of K519 into C519 can be attributed to the effect of K519C variation on the conversion rate constant between states. This work helps to understand the conductive mechanism of ClC-0. 2. 2. The effect of residue variation on the electrostatic binding free energy of chloride ions in ClC-ec1 was studied. The residue variation of ClC-channel protein led to the change of protein function and caused many diseases. It has been found that the function of ClC protein is closely related to the binding energy of chloride ions in the channel. Therefore, the effect of residue variation on the function of ClC-ec1 can be demonstrated by studying the effect of residue variation on the binding energy of chloride ions in the channel. We have systematically studied the effects of various residue variations on the binding energies of chloride ions in channels. By means of full atomic molecular dynamics simulation and electrostatic calculation, it is revealed that the change of charge caused by residue variation and the distance between residue and chloride binding sites are important factors affecting the binding energy of chlorine ions. At the molecular level, the effect of CLC channel protein residue variation on protein function has been recognized.
【学位授予单位】：武汉大学
【学位级别】：博士
【学位授予年份】：2010
【分类号】：R341

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