Papaleo Elena, Riccardi Laura, Villa Chiara, Fantucci Piercarlo, De Gioia Luca
Department of Biotechnology and Bioscience, University of Milano-Bicocca, P.za della Scienza 2, 20126, Milan, Italy.
Biochim Biophys Acta. 2006 Aug;1764(8):1397-406. doi: 10.1016/j.bbapap.2006.06.005. Epub 2006 Jul 1.
Molecular dynamics simulations of representative mesophilic and psycrophilic elastases have been carried out at different temperatures to explore the molecular basis of cold adaptation inside a specific enzymatic family. The molecular dynamics trajectories have been compared and analyzed in terms of secondary structure, molecular flexibility, intramolecular and protein-solvent interactions, unravelling molecular features relevant to rationalize the efficient catalytic activity of psychrophilic elastases at low temperature. The comparative molecular dynamics investigation reveals that modulation of the number of protein-solvent interactions is not the evolutionary strategy followed by the psycrophilic elastase to enhance catalytic activity at low temperature. In addition, flexibility and solvent accessibility of the residues forming the catalytic triad and the specificity pocket are comparable in the cold- and warm-adapted enzymes. Instead, loop regions with different amino acid composition in the two enzymes, and clustered around the active site or the specificity pocket, are characterized by enhanced flexibility in the cold-adapted enzyme. Remarkably, the psycrophilic elastase is characterized by reduced flexibility, when compared to the mesophilic counterpart, in some scattered regions distant from the functional sites, in agreement with hypothesis suggesting that local rigidity in regions far from functional sites can be beneficial for the catalytic activity of psychrophilic enzymes.
已在不同温度下对代表性的嗜温弹性蛋白酶和嗜冷弹性蛋白酶进行了分子动力学模拟,以探究特定酶家族内部冷适应的分子基础。已根据二级结构、分子柔韧性、分子内和蛋白质-溶剂相互作用对分子动力学轨迹进行了比较和分析,揭示了与合理化嗜冷弹性蛋白酶在低温下有效催化活性相关的分子特征。比较分子动力学研究表明,调节蛋白质-溶剂相互作用的数量并非嗜冷弹性蛋白酶在低温下增强催化活性所采用的进化策略。此外,在冷适应和热适应的酶中,形成催化三联体和特异性口袋的残基的柔韧性和溶剂可及性相当。相反,两种酶中具有不同氨基酸组成且聚集在活性位点或特异性口袋周围的环区域,在冷适应酶中具有增强的柔韧性。值得注意的是,与嗜温弹性蛋白酶相比,嗜冷弹性蛋白酶在远离功能位点的一些分散区域具有降低的柔韧性,这与认为远离功能位点区域的局部刚性对嗜冷酶的催化活性有益的假设一致。