Regulation and functional role of the electron transport chain supercomplexes

Abstract

Mitochondria are one of the most exhaustively investigated organelles in the cell and most attention has been paid to the components of the mitochondrial electron transport chain (ETC) in the last 100 years. The ETC collects electrons from NADH or FADH2 and transfers them through a series of electron carriers within multiprotein respiratory complexes (complex I to IV) to oxygen, therefore generating an electrochemical gradient that can be used by the F1-F0-ATP synthase (also named complex V) in the mitochondrial inner membrane to synthesize ATP. The organization and function of the ETC is a continuous source of surprises. One of the latest is the discovery that the respiratory complexes can assemble to form a variety of larger structures called super-complexes (SCs). This opened an unexpected level of complexity in this well-known and fundamental biological process. This review will focus on the current evidence for the formation of different SCs and will explore how they modulate the ETC organization according to the metabolic state. Since the field is rapidly growing, we also comment on the experimental techniques used to describe these SC and hope that this overview may inspire new technologies that will help to advance the field.

Physiological Doses of Hydroxytyrosol Modulate Gene Expression in Skeletal Muscle of Exercised Rats

“…It is important to highlight that HT can increase the amount of mitochondrial respiratory complexes into supercomplexes by a yet uncharacterized mechanism [14,32]. Our observation that HT prevents GLUT4 protein expression could provide a mechanistic link.…”

Overexpression of MRX9 impairs processing of RNAs encoding mitochondrial oxidative phosphorylation factors COB and COX1 in yeast

“…Mitochondria OXPHOS complexes can form large structures called supercomplexes ( 70 ), whose formation and stoichiometry is modulated by the metabolic state and energetic demand of the cell ( 71 ). In yeast, the two observed supercomplexes consist of the dimeric bc 1 complex associated with one or two cytochrome c oxidase complexes on either side of bc 1, while the ATP synthase dimers and oligomers are required for cristae formation ( 70 , 71 , 72 ). Mitochondrial supercomplexes are the final elements of a highly ordered orchestration of events, tightly regulated, involving mtDNA gene expression, mitochondrial protein import, and OXPHOS complexes assembly.…”

Bioenergetics and Reactive Nitrogen Species in Bacteria

“…The main function of the chains is to create a proton motive force (PMF), a central energy currency. The well-known mammalian mitochondrial chain is linear [18,19]. It consists of the enzyme complexes I, II, III, and IV (Table 1).…”