CAREER: The molecular interplay between integrin adhesion, allostery and shape-shifting

粘附分子是细胞表面的蛋白质，促进细胞粘附、迁移和与外界环境的相互作用。这些粘附分子，具体称为整合素，具有几乎相同的拓扑结构，并且在环境条件下非常熟练，精确和特异性。此外，它们是高度进化的，很容易适应新的机制。整合素α/β异二聚体在所有动物（从海绵到脊椎动物）中都有表达，结合不同的配体，并且在每种人类细胞类型中至少有一种整合素表达。由于缺乏表征其结构变化和细胞表面粘附特性的定量研究，每种整合素如何分化以发挥特定作用在很大程度上是未知的。这项研究将集中于确定白细胞特异性整合素受体的结构和粘附特性，这种受体仅存在于脊椎动物中。本研究将运用生物物理学、生物化学、结构生物学和化学等方法来研究白细胞整合素构象和粘附的变化。生物技术夏季研讨会是为K-12 STEM学生和正在培训成为未来STEM教师的本科生设计的，将提供对生物分子结构的基本理解，以及这些结构的改变如何与蛋白质功能相关。白细胞整合素以变构方式传递机械和生化信息，并调节许多细胞事件，包括白细胞迁移、向组织损伤或感染部位迁移和吞噬。白细胞整合素如何在变构调节其亲和力和结构的同时实现如此多样化的功能？本提案的总体目标是量化其在不同整合素构象之间的热力学平衡的构象动力学，测量占位和内在亲和力，并确定每个白细胞整合素构象状态的冷冻电镜结构。整合素动态变构事件的定量表征将极大地促进我们对整合素生物学的理解，为详细阐述整合素对不同功能的进化适应打开新的大门，并将有力地实现具有多种功能输出的更有效的蛋白质工程和效应器设计。该项目由分子和细胞生物科学部的分子生物物理集群资助。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Adhesion molecules are proteins on cell surfaces that facilitate cellular adhesion, migration, and interactions with the external environment. These adhesion molecules, specifically called integrins, share an almost identical topology and are highly proficient, precise, and specific at ambient conditions. Moreover, they are highly evolvable and easily adapt to new mechanisms. Integrin α/β heterodimers are expressed in all animals (from sponges to vertebrates), bind different ligands, and at least one integrin is expressed in each human cell type. Exactly how each integrin has been diverged to play a particular role is largely unknown due to the lack of quantitative studies characterizing their structural changes and adhesion properties on cell surfaces. This research will focus on defining the structural and adhesive properties of a white blood cell-specific integrin receptor, which is only present in vertebrate animals. This research will employ biophysics, biochemistry, structural biology, and chemistry approaches to relate the changes in this leukocyte integrin’s conformation and adhesion. The biotechnology summer workshop, designed for K–12 STEM students and undergraduates who are training to be future STEM teachers, will provide insight into the fundamental understanding of biomolecular structures and how alterations in these structures are related to protein function. Leukocyte integrins allosterically communicate mechanical and biochemical information and regulate many cellular events that involve leukocyte migration, diapedesis towards the site of tissue damage or infection, and phagocytosis. How do leukocyte integrins achieve such diverse functions while allosterically regulating their affinities and structures? The overarching objective of this proposal is to quantify its conformational kinetics that are thermodynamically equilibrated between different integrin conformations, measure the occupancy and intrinsic affinities, and determine cryo-EM structures of each leukocyte integrin conformational state. Quantitative characterization of the integrin dynamic allostery events would greatly advance our understanding of integrin biology, open new doors to elaborate integrin evolutionary adaptations to different functions and would be powerful in enabling both more efficient protein engineering with multiple functional outputs and effector design. This project is funded by the Molecular Biophysics Cluster in the Division of Molecular and Cellular Biosciences.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.