Study of AAA proteins by X-ray protein crystallography

细胞内蛋白降解是一种重要的翻译后调控机制，在许多重要的细胞功能中起着至关重要的作用；它还可以去除受损的、变性的和其他异常的蛋白质。与LCB的Maurizi博士合作，我的团队确定了全长ClpA的晶体结构，ClpAP复合物的调节成分。ClpA结构作为首个用两个AAA+模块测定的AAA+蛋白晶体结构，为两个AAA+模块功能差异的结构基础提供了深入的见解。我的团队还获得了ClpA与ClpS复合物中分离的n结构域的结构，已知该结构可以改变ClpA中的底物选择性，就像许多其他AAA+蛋白使用的接头蛋白一样（Maurizi和Xia， 2004）。我们还通过分析其多个蛋白质和肽结合位点的晶体学细节来定义ClpA n端结构域的功能（Xia et al., 2004）。在获得了ClpAPS体系中所有组分的结构后，我们的研究小组现在正专注于获得由结合核苷酸诱导的各种构象的ClpA结构，以及ClpA与ClpS或ClpP的二元配合物的结晶，以及与各种底物的结晶。

Intracellular protein degradation is a major post-translational regulatory mechanism and plays a crucial role in many vital cellular functions; it also serves to remove damaged, denatured, and other abnormal proteins. In collaboration with Dr. Maurizi at LCB, my group has determined the crystal structure of the full-length ClpA, the regulatory component of the ClpAP complex. As the first crystal structure of AAA+ protein to be determined with two AAA+ modules, the ClpA structure has provided insights into the structural basis for the functional difference of the two AAA+ modules. My group has also obtained the structure of the isolated N-domain of ClpA in complex with ClpS that is known to alter the substrate selectivity in ClpA, much like the adaptor proteins used by many other AAA+ proteins (Maurizi and Xia, 2004). We also defined the function of the ClpA N-terminal domain by analyzing crystallographically details of its multiple protein and peptide binding sites (Xia et al., 2004). Having obtained structures of all components in the ClpAPS system, our group is now focusing on obtaining structures of ClpA in various conformations induced by bound nucleotides, and on crystallizing binary complexes of ClpA with either ClpS or ClpP, as well as with various substrates.