Dynamics and Mechanism of Water-Protein Interactions

描述(申请人提供)：蛋白质水合作用是蛋白质科学中一个长期悬而未决的问题，水-蛋白质相互作用/动力学对蛋白质的结构、动力学和功能至关重要。在分子水平上阐明这种偶联运动不仅对理解蛋白质的稳定性和柔性、折叠、错折叠和聚集、识别和结合以及酶催化具有重要意义，而且对药物设计等实际应用也有重要影响。各种方法和策略已被用来表征蛋白质周围的水运动，但由于动力学的超快和异质性，这样的研究一直具有挑战性和难度。目前还没有得到一般的分子图景。我们最近开发了一种将最先进的飞秒激光光谱学和定点突变相结合的方法，并达到了飞秒时间分辨率和单残基空间分辨率。利用本征氨基酸色氨酸作为局部光学探针，我们最近以前所未有的细节绘制了一个a螺旋球状蛋白周围的全球水运动。在这个方案中，我们将系统地描述围绕小结构基序的水运动，在折叠球状蛋白质的表面上，以及在蛋白质-DNA复合体的界面上。具体地说，目标1是通过系统地描述水从a-螺旋到发夹、到小笼子和到微型蛋白质的运动来阐明水化动力学的演变。随着对这些基本结构单元周围的水运动的基本了解，在目标2中，我们扩展到描述两个片状球状蛋白质周围的全球表面水化动力学。结合最近表征的a-螺旋球状蛋白周围的水动力学，我们希望这种系统的比较将揭示不同大小、刚性、化学同一性的不同蛋白质结构周围水运动的不同动力学性质。最后，在目标3中，我们通过系统地描述两个蛋白质-DNA复合体界面上的水运动来研究界面水化动力学，以探讨水运动在蛋白质-DNA识别中的动力学作用。从这些系统研究中获得的新知识是各种生物过程的基础，也对一系列实际应用具有重要意义。

DESCRIPTION (provided by applicant): Protein hydration is a long-standing and unresolved problem in protein science and water-protein interactions/dynamics are essential to a protein's structure, dynamics and function. The elucidation of such coupling motions at the molecular level not only has fundamental significance in understanding protein stability and flexibility, folding, misfolding and aggregation, recognition and binding, and enzyme catalysis, but also has a significant impact on practical applications such as drug design. Various methods and strategies have been used to characterize water motions around proteins, but such studies have been challenging and difficult because the dynamics are ultrafast and heterogeneous. A general molecular picture has not been obtained yet. We have recently developed a methodology by integrating state-of-the-art femtosecond laser spectroscopy and site-directed mutagenesis and have reached femtosecond temporal resolution and single-residue spatial resolution. Using intrinsic amino acid tryptophan as a local optical probe, we have recently mapped out the global water motions around an a-helical globular protein with unprecedented details. In this proposal, we will systematically characterize water motions around small structural motifs, on surfaces of ¿-sheet globular proteins, and at interfaces of protein-DNA complexes. Specifically, Aim 1 is to elucidate the hydration dynamics evolution by systematic characterization of water motions from an a-helix, to a ¿-hairpin, to a small cage, and to a mini-protein. With the fundamental understanding of water motions around these elemental structure units, in Aim 2 we extend to characterize the global surface hydration dynamics around two ¿-sheet globular proteins. Combined with recently characterized water dynamics around the a-helical globular protein, we hope that such systematic comparisons will reveal the different dynamic nature of water motions around different protein architectures with different size, rigidity, chemical identity. Finally, in Aim 3, we investigate the interfacial hydration dynamics by systematic characterization of water motions at the interfaces of two protein-DNA complexes to address the dynamic role of water motions in mediation of protein-DNA recognition. The new knowledge obtained from these systematic investigations is fundamental to a wide variety of biological processes and also significant to a series of practical applications.