Protein free energy landscapes remodeled by ligand binding
Protein free energy landscapes remodeled by ligand binding
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DOI：
10.1529/biophysj.107.103911
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发表时间：
2007-07-01
影响因子：
3.4
通讯作者：
Talaga, David S.
中科院分区：
文献类型：
--
作者：
Messina, Troy C.;Talaga, David S.
葡萄糖/半乳糖结合蛋白（GGBP）在肠道细菌用于分子识别和信号传导的两个不同的蛋白质系统中起作用。本文报道了GGBP构象平衡分布的热力学。三种荧光成分出现在零葡萄糖浓度和系统转变为三种成分在高葡萄糖浓度。利用荧光各向异性相关性、荧光寿命、热力学、计算结构最小化和文献工作，将三种成分分配为蛋白质的开放、封闭和扭曲构象。在所有葡萄糖浓度下，三种状态的存在表明蛋白质通过热驱动的状态转变在其构象状态空间上连续波动；葡萄糖通过重新组织自由能分布而使总体偏倚。根据GGBP与细胞质膜蛋白的两种类型的特异性和非特异性相互作用，讨论了这些结果及其意义。
Glucose/galactose binding protein (GGBP) functions in two different larger systems of proteins used by enteric bacteria for molecular recognition and signaling. Here we report on the thermodynamics of conformational equilibrium distributions of GGBP. Three fluorescence components appear at zero glucose concentration and systematically transition to three components at high glucose concentration. Fluorescence anisotropy correlations,fluorescent lifetimes, thermodynamics, computational structure minimization, and literature work were used to assign the three components as open, closed, and twisted conformations of the protein. The existence of three states at all glucose concentrations indicates that the protein continuously fluctuates about its conformational state space via thermally driven state transitions; glucose biases the populations by reorganizing the free energy profile. These results and their implications are discussed in terms of the two types of specific and nonspecific interactions GGBP has with cytoplasmic membrane proteins.