Structural studies of intramembrane protease GlpG

描述(申请人提供)：膜内蛋白分解是细胞生物学中一种重要且广泛的生化机制：许多膜蛋白经过膜内蛋白分解以激活信号转导，或转化为可能导致人类疾病的难溶淀粉样多肽。这一提议的长期目标是通过对催化反应的特定膜蛋白及其与抑制剂和底物的络合物的结晶学分析来更深入地了解这一机制。许多膜内蛋白水解酶已被认为是治疗感染性和老年性疾病的新的和重要的药物靶点。目前的应用主要集中在GlpG，这是一种菱形丝氨酸蛋白酶家族的大肠杆菌完整膜蛋白。计划通过生化、诱变和结晶学实验研究：(1)GlpG如何与特定类别的抑制剂相互作用，以检验GlpG和其他菱形蛋白酶利用膜包埋的Ser-His二聚体直接攻击底物的假设，并确定对催化起重要作用的蛋白酶活性部位的特征；(2)GlpG如何通过两种蛋白质中的复杂结构重排与跨膜底物相互作用，以及哪些因素决定了这种相互作用的特异性；以及(3)一个有趣的结构基序调节膜中的蛋白酶活性的机制。最近在GlpG晶体结构测定方面的突破表明，这种细菌膜蛋白是研究细胞膜中酶作用的一个很好的模型系统。

DESCRIPTION (provided by applicant): Intramembrane proteolysis is an important and widespread biochemical mechanism in cell biology: many membrane proteins undergo intramembrane proteolysis to become activated for signal transduction, or to be converted to poorly soluble amyloidal peptides that may cause human disease. The long-term objective of this proposal is to gain a deeper understanding of this mechanism through crystallographic analysis of specific membrane proteins that catalyze the reaction and of their complexes with inhibitors and substrates. Many intramembrane proteases have been recognized as novel and important drug targets for treating infectious and age-related diseases. The current application focuses on GlpG, an E. coli integral membrane protein of the rhomboid serine protease family. Biochemical, mutagenesis and crystallographic experiments are planned to study: (1) how GlpG interacts with class specific inhibitors in order to examine hypothesis that GlpG and other rhomboid proteases use a membrane-embedded Ser-His dyad to directly attack substrate, and to determine features of the protease active site that are important for catalysis; (2) how GlpG interacts with transmembrane substrates through complex structural rearrangements in both proteins, and which factors determine the specificity of this interaction; and (3) the mechanism by which an interesting structural motif regulates protease activity in the membrane. Recent breakthroughs in crystal structure determination of GlpG suggest that this bacterial membrane protein is an excellent model system for studying enzyme action in cell membranes.