Understanding transmembrane helix interaction on the structural level

描述（由申请人提供）：了解跨膜（TM）螺旋如何相互识别是一个重要而具有挑战性的问题。在这里，我建议利用整合素系统来研究TM螺旋相互作用偏好的结构和序列决定因素。整合素是一种二聚体单遍膜蛋白家族，作为细胞粘附受体。已知整合素至少以两种状态存在——一种是活性状态，它们与细胞外配体结合；另一种是非活性状态，这种结合不会发生。研究表明，干扰整合素TM螺旋二聚化的肽，通过与其中一种单体相互作用，导致整合素激活。持续地从头设计这种肽的能力关键取决于我们对TM螺旋相互作用偏好的理解。因此，为了研究这些偏好，我将在这些肽的计算设计和它们的实验表征之间建立一个循环。我将设计：1)通过与α亚基相互作用来破坏alpha2beta1和alpha4beta1的TM螺旋结合的肽；2)通过与天然二聚体形成三聚体螺旋束来稳定alphabbetas的TM螺旋结合的肽。我还将利用整合素是一个多样化的家族（在脊椎动物中已知有18个α亚基和8个β亚基）的事实来研究设计TM螺旋相互作用特异性的问题。整合素参与了许多生物关键过程，并与癌症血管生成和转移以及各种出血性疾病等人类疾病有关。通过解读整合素TM相互作用特异性的原理，这项工作将提出选择性激活或失活特定受体的方法，这可能导致新的治疗方法。此外，了解TM螺旋相互作用的决定因素一般将对解剖跨膜蛋白质折叠和相互作用产生更广泛的影响。公共卫生相关性：整合素是一个蛋白质家族，参与多种生物过程和人类疾病，从免疫反应和白细胞运输到癌症、发育和印迹凝血。整合素功能的核心是它们的跨膜（TM）区域之间的联系。这项工作将阐明TM区域相互识别的原理，这将提供一种控制整合素活性的方法，并可能导致新的治疗方法。

DESCRIPTION (provided by applicant): Understanding how transmembrane (TM) helices recognize each other is an important and challenging problem. Here I propose to utilize the integrin system to study structural and sequence determinants of TM helix interaction preferences. Integrins are a family of dimeric single-pass membrane proteins that act as cell adhesion receptors. Integrins are known to exist in at least two states - an active state, where they bind extracellular ligands and an inactive state, where this binding does not occur. It has been shown that peptides that interfere-with the dimerization of integrin TM helices, by interacting with one of the monomers, cause integrin activation. The ability to consistently design such peptides de novo critically depends on our understanding of TM helix interaction preferences. Therefore, to study these preferences, I will establish a cycle between the computational design of such peptides and their experimental characterization. I will design: 1) peptides that disrupt the TM helix association of alpha2beta1 and alpha4beta1 by interacting with the alpha subunits and 2) peptides that stabilize the TM helix association of alphallbbetaS by forming a trimeric helix bundle with the native dimer. I will also make use of the fact that integrins are a diverse family (with 18 alpha and 8 beta subunits known in vertebrates) to study the problem of designing TM helix interaction specificity. Integrins are involved in many biologically critical processes and are associated with such human conditions as cancer angiogenesis and metastasis and various bleeding disorders. By deciphering the principles of integrin TM interaction specificity, this work will suggest ways to selectively activate or deactivate particular receptors, which can lead to novel therapies. Additionally, understanding the determinants of TM helix interactions in general will have a wider impact on dissecting transmembrane protein folding and interaction. PUBLIC HEALTH RELEVANCE: Integrins are a family of proteins that that are involved in a great variety of biological processes and human diseases, from immune response and leukocyte trafficking to cancer, development and blot clotting. Central to the function of integrins is the association between their transmembrane (TM) regions. This work will shed light on the principles by which TM regions recognize each other, which will provide a way of controlling integrin activity and will likely lead to novel therapies.