Assembly mechanism of cochaperone-kinase complexes

 描述（由申请人提供）：Hsp 90与称为辅伴侣的其他蛋白质一起形成控制多种底物或客户的构象成熟的分子机制。Hsp 90介导的伴侣循环发生在蛋白质折叠的后期阶段，以增加客户端稳定性和/或引发促进“伴侣”结合和/或导致客户端激活的精细结构变化。它开始于客户识别，招聘人员陪同，随后客户转移到HSP 90。然后辅伴侣蛋白被释放，并且客户端重塑和从Hsp 90释放伴随着Hsp 90的大的构象变化。这些顺序步骤之间的进展是精细调制的存在下，其他cochaperones，结合到热休克蛋白90和翻译后修饰的核苷酸的身份。在分子水平上，热休克蛋白90的相互作用与它的cochaperones和构象变化与其ATP酶循环的特点是在原子分辨率。虽然这些研究对我们全面了解分子伴侣的功能做出了重大贡献，但底物参与分子伴侣循环的分子机制仍然知之甚少。在Hsp 90介导的激酶伴侣化的第一步中，Cdc 37是与Hsp 90相关的普遍存在的底物募集者辅伴侣，以赋予激酶特异性。尽管Cdc 37在激酶伴侣中起着重要作用，但人们对Cdc 37识别蛋白激酶、将依赖于Hsp 90的激酶与不依赖于Hsp 90的激酶分类并将其传递给Hsp 90的分子机制知之甚少。我们将使用一个多学科的方法，其中高分辨率的结构和动态信息，从NMR光谱，将结合热力学和动力学的协会，以及在体内的功能测定，阐明的分子机制，使Cdc 37控制激酶进入热休克蛋白90分子伴侣循环。具体的目标是解决以下问题：（1）Cdc 37的结构和动力学特性;（2）Cdc 37如何识别蛋白激酶的催化结构域;（3）Cdc 37如何区分Hsp 90依赖性和Hsp 90非依赖性激酶？

 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?