Modular assembly of cytochrome oxidase

细胞色素氧化酶的模块化组装

• 批准号: 9113956
• 负责人: ALEXANDER A TZAGOLOFF
• 金额: $ 22.4万
• 依托单位: COLUMBIA UNIV NEW YORK MORNINGSIDE
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-09-05 至 2018-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9113956
• 关键词: Address; Assimilations; Biochemical; Biogenesis; Catalytic Domain; Cells; Collaborations; Collection; Complex; Cytochrome-c Oxidase Deficiency; Electrons; Enzymes; Equilibrium; Food; Genes; Genetic; Health; Holoenzymes; Human; Inner mitochondrial membrane; Knowledge; Label; Laboratories; Membrane; Mining; Mitochondria; Modeling; Multienzyme Complexes; Nuclear; Output; Oxygen; Pathway interactions; Peripheral; Physiologic pulse; Play; Process; Respiratory Chain; Role; Series; Source; Staging; System; Testing; Translating; Translations; Water; Yeast Model System; Yeasts; aggregation pathway; base; cytochrome c oxidase; gene product; genetic information; genetic regulatory protein; interest; mutant; polypeptide; respiratory; stoichiometry

DESCRIPTION (provided by applicant): Cytochrome oxidase (COX), the terminal complex of the respiratory chain, consists of 11 different subunit polypeptides. The mitochondrially encoded Cox1p, Cox2p and Cox3p subunits constitute the catalytic core while eight other structural subunits are products of nuclear genes. Because of its genetic and compositional complexity, biogenesis of COX is a highly integrated process that is assisted by numerous accessory proteins and regulatory factors for coordinating a balanced output of compartmentally separated genes. Pulse-chase studies with isolated mitochondria have shown that prior to their assimilation into COX, Cox1p and Cox3p, each, transitions through a series of intermediates differentiated by their compositions of accessory factors and structural subunits. This finding has led us to propose a biogenesis model involving three separate pathways with modular products that ultimately combine to form the holoenzyme. This proposal has four objectives, each related to an important facet of COX biogenesis. 1) We wish to consolidate the modular assembly model with direct experimental evidence that Cox2p also preassembles as an independent module. This will be addressed by identifying and characterizing Cox2p intermediates in pulse-chase labeled mitochondria. 2) We have indirect evidence that mitochondrial gene products of COX and the bc1 complex, both of which exist in a supercomplex, are inserted in the same or neighboring subcompartments of the membrane during their biogenesis. This suggests that assembly of the COX/bc1 supercomplex may be coordinated both physically and temporally. We will test this hypothesis by genetic and biochemical means. 3) Some recent results suggest that the proper stoichiometry of COX and ATP synthase may be achieved via a complex of the rotor subunit Atp9p and the COX peripheral subunit Cox6p. We will further test this interesting possibility by studying assembly of the ATP synthase in cox6 null mutants and conversely of COX assembly in atp9 mutants. 4) Much of our current knowledge of COX biogenesis has come from functional studies of accessory factors that intervene at different stages of the Cox1p-Cox3p assembly pathways. Many but not all of these factors were identified through studies of yeast mutants displaying a specific deficiency in COX. The fourth and last objective of this proposal is to continue mining a collection of nuclear respiratory defective yeast pet mutants for still undiscovered genes essential for COX biogenesis. These studies will enlarge our understanding of the mechanisms and the factors that govern assembly of an important mitochondrial respiratory complex derived from genetic information residing in two spatially distinct compartments of the cell.

描述（由申请人提供）：细胞色素氧化酶（COX），呼吸链的末端复合体，由11个不同的亚基多肽组成。线粒体编码的Cox1p、Cox2p和Cox3p亚基构成催化核心，其他8个结构亚基是核基因的产物。由于其遗传和组成的复杂性，COX的生物发生是一个高度整合的过程，它由许多辅助蛋白和调节因子辅助，以协调区隔分离基因的平衡输出。对分离线粒体的脉冲追踪研究表明，在同化为COX、Cox1p和Cox3p之前，它们分别通过一系列由辅助因子和结构亚基组成的中间产物进行转变。这一发现