Structural study of the Ly49A T cell recognition domain

Ly49A T细胞识别域的结构研究

• 批准号: 7593498
• 负责人: Ad - Bax
• 金额: $ 21.68万
• 依托单位: NATIONAL INSTITUTE OF DIABETES AND DIGESTIVE AND KIDNEY DISEASES
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/7593498
• 关键词: Address; Adopted; Agreement; Binding; Cell physiology; Cells; Class; Coupling; Detection; Family; Individual; KLRA1 gene; Major Histocompatibility Complex; Molecular Conformation; Natural Killer Cells; Play; Role; Solutions; Structure; T-Lymphocyte; Technology; Variant; analytical ultracentrifugation; dimer; neoplastic cell; receptor; receptor binding; research study; sedimentation velocity; Address; Adopted; Agreement; Binding; Cell physiology; Cells; Class; Coupling; Detection; Family; Individual; KLRA1 gene; Major Histocompatibility Complex; Molecular Conformation; Natural Killer Cells; Play; Role; Solutions; Structure; T-Lymphocyte; Technology; Variant; analytical ultracentrifugation; dimer; neoplastic cell; receptor; receptor binding; research study; sedimentation velocity

Previous crystal studies revealed that the Ly49A homodimer binds one MHC molecule in an asymmetric interaction, whereas the Ly49C homodimer binds two MHC in a symmetrical fashion. Moreover, the bound receptors adopt distinctly different homodimeric forms: a closed state for Ly49A and an open state for Ly49C. Steric clashes between MHC molecules would preclude the closed Ly49A dimer from engaging two MHC in the manner of the open Ly49C dimer. To address whether individual Ly49 receptors can undergo a conformational switch enabling them to bind MHC in different ways, we carried out a solution NMR study of unbound Ly49A, aided by dipolar coupling technology. This study reveals that in solution unligated Ly49A adopts a symmetric, open state, homodimer conformation similar to that previously seen for Ly49C. Hence, Ly49A can assume both closed and open states. To address whether the Ly49A dimer can bind two MHC molecules in solution, besides the binding of one MHC observed in the crystal, we carried out analytical ultracentrifugation experiments. Velocity sedimentation demonstrates that the Ly49A dimer can engage two MHC in solution, in agreement with NMR results showing that unbound Ly49A exists predominantly in the open state.

先前的晶体研究表明，LY49A同型二聚体在不对称相互作用中结合了一个MHC分子，而LY49C同型二聚体以对称方式结合了两个MHC。此外，结合受体采用明显不同的同型二聚体形式：ly49a的封闭状态和ly49c的开放状态。 MHC分子之间的空间冲突将阻止封闭的LY49A二聚体以开放的LY49C二聚体的方式与两个MHC接合。为了解决单个LY49受体是否可以经历构象开关，使其能够以不同的方式绑定MHC，我们通过偶极耦合技术进行了对未结合LY49A的溶液NMR研究。这项研究表明，在溶液中，ly49a在溶液中采用了一种对称，开放状态，同二聚体构象，类似于先前对LY49C的构象。 因此，LY49A可以假定封闭状态和开放状态。为了解决Ly49a二聚体是否可以在溶液中结合两个MHC分子，除了在晶体中观察到的一个MHC的结合外，我们进行了分析性超速离心实验。速度沉积表明LY49A二聚体可以与NMR结果一致，表明未结合的LY49A主要存在于开放状态。