Sep 16: Supercomplex, an Emerging Mechanism for Mitochondrial Respiration

Speaker： Yidong Bai

Host: Prof. Jiemin Wong

When: 2013-9-16 13:30

Where: Conference Room 534, School of Life Sciences

Abstract：The primary function of mitochondrial function is to generate ATP through oxidative phosphorylation (OXPHOS). The composition of OXPHOS system has been fully illustrated, and structures of all individual complexes have been solved. However the organization and, in particular, the dynamics of this bioenergetics machinery has not been well-explored. Recently novel organization of respiratory machinery, supercomplex which contains multiple respiratory complexes has been identified. In this study, combing pulse-chase labeling with 2 D Blue Native PAGE (BN-PAGE) analysis6, we carefully investigated the assembly and turn-over of individual complexes and supercomplexes of respiratory chain in various mammalian cell systems. Among the electron transfer chain system, contrarily to previous reported, the biggest complex I is the first to be assembled, in the form of precursor, while complex III is the rate-limiting component of  the supercomplexes, which almost co-assembles with the supercomplexes. Our results also demonstrate that while other complexes are relatively stable by themselves, respiratory complex I mostly exists as part of supercomplexes, and the supercomplexes  I1 III2, and I1III2IV1 are also more stable than their components. These results indicate that there is common machinery for respiratory complexes assembly, and supercomplexes are the major functional respirasomes.