Structural and functional insights into the cofactor diversity of the human AAA ATPase p97

六聚体ATP酶p97参与多种细胞过程，包括细胞周期控制、膜融合、转录激活、DNA修复、凋亡、自噬以及泛素蛋白酶体系统。p97通过多种辅因子的结合介导这些不同的细胞过程，迄今为止已经鉴定了20多种辅因子。这些蛋白质主要与p97的N-末端辅因子结合结构域（N结构域）结合，但也与p97的非结构化C末端结合。涉及N结构域的相互作用通过“泛素调节X”（UBX）和泛素样结合结构域（ULD）或通过几个短的线性结合基序之一来介导。在这一点上，控制辅因子选择性的原则在很大程度上仍然难以捉摸。破译这种相互作用对于理解p97的多种生理作用及其在癌症以及各种神经退行性疾病（如帕金森病和亨廷顿病）中的作用至关重要。本论文将结合生物化学、生物物理学和结构学的研究方法，研究p97辅因子结合和特异性的机制，以及辅因子之间的竞争和协同作用，主要目的如下：（1）我们将破译p97辅因子识别其N结构域的结构多样性。(2)我们将研究p97及其各种辅因子的组装是如何组织的。(3)我们将在结构上表征p97-辅因子分子机器。

The hexameric ATPase p97 participates in a variety of cellular processes including cell-cycle control, membrane fusion, transcriptional activation, DNA repair, apoptosis, autophagy as well as the ubiquitin proteasome system. p97 mediates these diverse cellular processes through the binding of multiple cofactors of which more than 20 have been identified so far. These proteins predominantly bind to the p97 N-terminal cofactor binding domain (N domain) but also to the unstructured Cterminus of p97. Interactions involving the N domain are mediated either via “ubiquitin regulatory X” (UBX) and ubiquitin-like binding domains (ULD), or through one of several short linear binding motifs. At this point the principles governing cofactor selectivity largely remain elusive. Deciphering the interactions will be crucial to understand the multiple physiological roles of p97 and its involvement in cancer as well as a wide variety of neurodegenerative disorders such as Parkinson’s and Huntington’s disease. Through a combination of biochemical, biophysical and structural approaches we will study the mechanisms underlying p97 cofactor binding and specificity, as well as the competition between cofactors or their synergistic binding to p97 via the following aims: (1) We will decipher the structural diversity of p97 cofactors recognizing its N domain. (2) We will study how the assembly of p97 with its various cofactors is organized. (3) We will structurally characterize p97- cofactor molecular machines.