Assembly mechanism of cochaperone-kinase complexes

 描述(申请人提供)：HSP90与其他称为辅分子伴侣的蛋白质一起，形成一种分子机制，控制各种底物或客户的构象成熟。Hsp90介导的伴侣环发生在蛋白质折叠的后期，以增加客户的稳定性和/或引起精细的结构变化，从而促进“伙伴”结合和/或导致客户的激活。它从客户识别开始，招聘人员辅佐，然后客户转移到HSP90。然后，辅伴侣被释放，客户重塑和从Hsp90释放伴随着Hsp90的大量构象变化。这些连续步骤之间的进程受到其他辅伴侣的存在、与Hsp90结合的核苷酸的同一性和翻译后修饰的精细调控。在分子水平上，Hsp90与其辅助伴侣的相互作用以及与其ATPase循环相关的构象变化已经在原子分辨率上得到了表征。虽然这些研究对我们全面了解伴侣的功能有很大的贡献，但底物参与伴侣循环的分子机制仍然知之甚少。在Hsp90介导的激酶伴侣的第一步中，CDC37是与Hsp90相关的普遍存在的底物征募辅伴侣，以赋予激酶特异性。尽管CDC37在蛋白激酶伴侣中起着核心作用，但人们对其识别蛋白激酶、从依赖于Hsp90的蛋白激酶中筛选出依赖于Hsp90的蛋白并将其传递给Hsp90的分子机制知之甚少。我们将使用多学科方法，其中来自核磁共振光谱的高分辨率结构和动态信息将与热力学和结合动力学以及体内功能分析相结合，以阐明允许CDC37控制激酶进入Hsp90伴侣循环的分子机制。这些特定的目的是为了解决以下问题：(1)CDC37的结构和动力学性质是什么；(2)CDC37如何识别蛋白激酶的催化结构域；(3)CDC37如何区分Hsp90依赖和Hsp90非依赖的激酶？

 DESCRIPTION (provided by applicant): Hsp90 in cohort with other proteins termed cochaperones, forms a molecular machinery that controls the conformational maturation of a diverse array of substrates or clients. The Hsp90-mediated chaperone cycle occurs at a late stage of protein folding to increase client stability and/or to elicit fine structural changes whic facilitate "partner" binding and/or result in client activation. It begins with client recognition y a recruiter cochaperone and subsequent client transfer to Hsp90. The cochaperone is then released and client remodeling and release from Hsp90 is accompanied by large conformational changes of Hsp90. Progression between these sequential steps is finely modulated by the presence of other cochaperones, the identity of the nucleotide bound to Hsp90 and post-tranlational modifications. At a molecular level, the interaction of Hsp90 with its cochaperones and the conformational changes associated with its ATPase cycle have been characterized at atomic resolution. Although these studies have contributed significantly to our overall understanding of the function of the chaperone, the molecular mechanism by which substrates become engaged into the chaperone cycle remains poorly understood. During the first step of Hsp90-mediated kinase chaperoning, Cdc37 is the ubiquitous substrate recruiter cochaperone associated with Hsp90 to confer kinase specificity. Despite its central role in kinase chaperoning, little is known about the molecular mechanism by which Cdc37 recognizes protein kinases, sorts Hsp90-dependent from Hsp90-independent kinases and delivers them to Hsp90. We will use a multidisciplinary approach, where high resolution structural and dynamic information from NMR spectroscopy, will be combined with thermodynamics and kinetics of association, as well as, with in vivo functional assays, to elucidate the molecular mechanism that allows Cdc37 to control kinase entry into the Hsp90 chaperone cycle. The specific aims are designed to address the following questions (1) what are the structural and dynamic properties of Cdc37; (2) how does Cdc37 recognizes the catalytic domain of protein kinases; and (3) how Cdc37 differentiates between Hsp90-dependent and Hsp90-independent kinases?