Structure and Function of Mitochondrial Protein Kinase

超出所提供的空间。该项目的长期目标是了解一个新的线粒体蛋白激酶（mPKs）家族的结构和功能。mPK成员由支链α-酮酸脱氢酶激酶（BCK）和丙酮酸脱氢酶激酶的四种亚型组成。它们是下调α-酮酸和丙酮酸氧化的分子开关。这些代谢物水平升高与胰岛素抵抗型II型糖尿病、支链酮酸尿症和原发性乳酸酸中毒等疾病状态有关。BCK是线粒体支链α-酮酸脱氢酶（BCKD）复合物的组分。这种大分子多酶复合物围绕24梅里克转酰酶（E2 b）支架组织，脱羧酶（Elb）、脱氢酶（E3）、BCK和BCKD磷酸酶通过离子相互作用连接到该支架上。私家侦探实验室最近确定了大鼠BCK的结构。BCK结构具有特征性的核苷酸结合结构域和四螺旋束结构域。这两个结构域使人想起蛋白质组氨酸激酶（PHK）中发现的模块，其参与双组分信号转导系统。在本申请中，P.I.建议：1）鉴定和表征BCK中与BCKD复合物的E1 b（底物）和E2 b（调节剂）组分相互作用的结构域/区域; 2）破译BCK中核苷酸诱导的结构域通讯的功能意义; 3）阐明BCK催化ATP水解和磷酸转移的反应机制。这些结果将为研究可逆磷酸化对O_-酮酸脱氢酶复合物的调控机制提供理论依据。这些知识将对理解参与信号转导的蛋白激酶的反应机制的保守性以及这种机制在人类疾病中是如何受到干扰产生广泛的影响。性能现场=

EXCEED THE SPACE PROVIDED. The long-term goal of this project is to understand the structure and function of a novel family of mitochondrial protein kinases (mPKs). The mPK members consist of branched-chain ct-ketoacid dehydrogenase kinase (BCK) and the four isoforms of pyruvate dehydrogenase kinase. They are molecular switches that down-regulate the oxidation of 0c-ketoacids and pyruvate. Elevated levels of these metabolites are implicated in disease states such as insulin-resistant Type II diabetes, branched-chain ketoaciduria, and primary lactic acidosis. BCK is a component of the mitochondrial branched-chain oc-ketoacid dehydrogenase (BCKD) complex. This macromolecular multi-enzyme complex is organized about a 24-meric transacylase (E2b) scaffold, to which a decarboxylase (Elb), a dehydrogenase (E3), the BCK and the BCKD phosphatase are attached through ionic interactions. The P.I.'s laboratory has recently determined the structure of the rat BCK. The BCK structure features a characteristic nucleotide-binding domain and a four-helix bundle domain. These two domains are reminiscent of modules found in protein histidine kinases (PHKs), which are involved in two-component signal transduction systems. In this application, the P.I. proposes: 1) to identify and characterize the domains/regions in BCK, which interact with Elb (the substrate) and E2b (the regulator) components of the BCKD complex; 2) to decipher the functional significance of nucleotide-induced domain communication in BCK; 3) to elucidate the reaction mechanisms for the BCK-catalyzed ATP hydrolysis and phosphotransfer in BCK. The information derived from the proposed studies will provide mechanistic insights into the regulation of o_-ketoacid dehydrogenase complexes by reversible phosphorylation. This knowledge will have wide implications for understanding conservation in the reaction mechanism for protein kinases involved in signal transduction as well as how this mechanism is perturbed in human diseases. PERFORMANCE SITE ========================================Section End===========================================