Kay L E, Muhandiram D R, Farrow N A, Aubin Y, Forman-Kay J D
Protein Engineering Network Centres of Excellence, University of Toronto, Ontario, Canada.
Biochemistry. 1996 Jan 16;35(2):361-8. doi: 10.1021/bi9522312.
Protein-protein interfaces can consist of interactions between large numbers of residues of each molecule; some of these interactions are critical in determining binding affinity and conferring specificity, while others appear to play only a marginal role. Src-homology-2 (SH2) domains bind to proteins containing phosphorylated tyrosines, with additional specificity provided by interactions with residues C-terminal to the phosphotyrosine (pTyr) residue. While the C-terminal SH2 domain of phospholipase C-gamma 1 (PLCC SH2) interacts with eight residues of a pTyr-containing peptide from its high affinity binding site on the beta-platelet-derived growth factor receptor, it can still bind tightly to a phosphopeptide containing only three residues. Novel deuterium (2H) based nuclear magnetic resonance (NMR) spin relaxation experiments which probe the nanosecond-picosecond time scale dynamics of methyl containing side chain residues have established that certain regions of the PLCC SH2 domain contacting the residues C-terminal to the pTyr have a high degree of mobility in both the free and peptide complexed states. In contrast, there is significant restriction of motion in the pTyr binding site. These results suggest a correlation between the dynamic behavior of certain groups in the PLCC SH2 complex and their contribution to high affinity binding and binding specificity.
蛋白质-蛋白质界面可由每个分子的大量残基之间的相互作用组成；其中一些相互作用对于确定结合亲和力和赋予特异性至关重要，而其他相互作用似乎仅起边缘作用。Src同源2（SH2）结构域与含有磷酸化酪氨酸的蛋白质结合，与磷酸酪氨酸（pTyr）残基C端的残基相互作用可提供额外的特异性。虽然磷脂酶C-γ1的C端SH2结构域（PLCγ1 SH2）与其在β-血小板衍生生长因子受体上的高亲和力结合位点的含pTyr肽的八个残基相互作用，但它仍可紧密结合仅含三个残基的磷酸肽。基于新型氘（2H）的核磁共振（NMR）自旋弛豫实验探测了含甲基侧链残基的纳秒至皮秒时间尺度动力学，结果表明，PLCγ1 SH2结构域中与pTyr C端残基接触的某些区域在游离态和肽复合态均具有高度的流动性。相比之下，pTyr结合位点的运动受到显著限制。这些结果表明，PLCγ1 SH2复合物中某些基团的动态行为与其对高亲和力结合和结合特异性的贡献之间存在相关性。
