Study of AAA proteins by X-ray protein crystallography

我的实验室首先确定了全长ClpA的结构，这也是II型AAA+蛋白的第一个结构，其特征是具有两个串联连接的AAA+模块。我们还确定了ClpA的n端结构域（N-domain）及其与ClpS的复合物的结构，ClpS是一种选择底物（n端规则）进行降解的衔接蛋白。我们分析了n结构域的结构，并确定了其与底物相互作用的潜在位点。最近，我的实验室已经确定了人类AAA+蛋白p97 atp酶突变体的N-D1片段的结构，这些突变体是在患有IBMPFD的患者中发现的。我们首次发现，当d1结构域与ATP结合时，突变蛋白的n端结构域具有不同的构象。这与之前在野生型酶中观察到的恒定n结构域构象与D1结构域的恒定结合ADP形成对比。我们的实验进一步表明，突变蛋白很可能改变了对各种核苷酸的亲和力，从而导致观察到的不稳定构象改变。我们认为p97中新观察到的构象对于理解其功能至关重要。更多的生物化学和结构实验正在进行，以证实全长p97蛋白的这一发现。

My lab was the first to determine the structure of the full-length ClpA, which was also the first structure of type II AAA+ proteins, which are characterized by having two tandem connected AAA+ modules. We also determined the structures of the N-terminal domain (N-domain) of ClpA and its complex with ClpS, an adaptor protein that plays a role in selecting substrates (N-end rule) for degradation. We analyzed the structure of the N-domain and identified potential sites for its interaction with substrates. Recently, my lab has determined structures for a number of N-D1 fragments of the human AAA+ protein p97 ATPase mutants, which were identified in patients suffering from the IBMPFD. We found for the first time that the N-terminal domains of mutant proteins take a different conformation when the D1-domains are bound with ATP. This is in contrast to previously observed invariable N-domain conformation with invariably bound ADP in the D1 domains in the wild type enzyme. Our experiments further suggest that mutant proteins most likely have altered affinities for various nucleotides that lead to the observed erratic conformational alteration. We believe that the new observed conformation in p97 is critical for understanding its function. More experiments, both biochemical and structural, are being conducted to confirm this find with the full-length p97 protein.