Identification of a Protein Mediating Respiratory Supercomplex Stability

Chen, Yu Chan; Taylor, Eric B.; Dephoure, Noah; Heo, Jin Mi; Tonhato, Aline; Papandreou, Ioanna; Nath, Nandita; Denko, Nicolas C.; Gygi, Steven P.; Rutter, Jared

doi:10.1016/j.cmet.2012.02.006

Cited by 199 publications

(302 citation statements)

References 37 publications

Supporting

Mentioning

287

Contrasting

Unclassified

Order By: Relevance

“…Although the metabolic switch from mitochondrial respiration to anaerobic glycolysis is widely recognized (1-4), several recent reports have shown that hypoxic stimuli unexpectedly increase OXPHOS efficiency as well (5)(6)(7). In other words, cells have adaptive mechanisms to maintain intracellular ATP levels by enhancing OXPHOS, particularly in the early phase of hypoxia, in which the O 2 supply is limited but still remains.…”

mentioning

confidence: 99%

Evaluation of intramitochondrial ATP levels identifies G0/G1 switch gene 2 as a positive regulator of oxidative phosphorylation

Kioka¹,

Kato²,

Fujikawa

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

The oxidative phosphorylation (OXPHOS) system generates most of the ATP in respiring cells. ATP-depleting conditions, such as hypoxia, trigger responses that promote ATP production. However, how OXPHOS is regulated during hypoxia has yet to be elucidated. In this study, selective measurement of intramitochondrial ATP levels identified the hypoxia-inducible protein G0/G1 switch gene 2 (G0s2) as a positive regulator of OXPHOS. A mitochondria-targeted, FRET-based ATP biosensor enabled us to assess OXPHOS activity in living cells. Mitochondria-targeted, FRET-based ATP biosensor and ATP production assay in a semiintact cell system revealed that G0s2 increases mitochondrial ATP production. The expression of G0s2 was rapidly and transiently induced by hypoxic stimuli, and G0s2 interacts with OXPHOS complex V (F o F 1 -ATP synthase). Furthermore, physiological enhancement of G0s2 expression prevented cells from ATP depletion and induced a cellular tolerance for hypoxic stress. These results show that G0s2 positively regulates OXPHOS activity by interacting with F o F 1 -ATP synthase, which causes an increase in ATP production in response to hypoxic stress and protects cells from a critical energy crisis. These findings contribute to the understanding of a unique stress response to energy depletion. Additionally, this study shows the importance of assessing intramitochondrial ATP levels to evaluate OXPHOS activity in living cells.energy metabolism | live-cell imaging M aintaining cellular homeostasis and activities requires a stable energy supply. Most eukaryotic cells generate ATP as their energy currency mainly through the mitochondrial oxidative phosphorylation (OXPHOS) system. The OXPHOS system consists of five large protein complex units (i.e., complexes I-V), comprising more than 100 proteins. In this system, oxygen (O 2 ) is essential as the terminal electron acceptor for complex IV to finally produce the proton-motive force that drives the ATPgenerating molecular motor complex V (F o F 1 -ATP synthase).Hypoxia causes the depletion of intracellular ATP and triggers adaptive cellular responses to help maintain intracellular ATP levels and minimize any deleterious effects of energy depletion. Although the metabolic switch from mitochondrial respiration to anaerobic glycolysis is widely recognized (1-4), several recent reports have shown that hypoxic stimuli unexpectedly increase OXPHOS efficiency as well (5-7). In other words, cells have adaptive mechanisms to maintain intracellular ATP levels by enhancing OXPHOS, particularly in the early phase of hypoxia, in which the O 2 supply is limited but still remains. However, the mechanism by which OXPHOS is regulated during this early hypoxic phase is still not fully understood.Revealing the mechanism of this fine-tuned regulation of OXPHOS requires accurate and noninvasive measurements of OXPHOS activity. Although researchers have established methods to measure OXPHOS activity, precise measurement, especially in living cells, is still difficult. Measuring the intracellul...

show abstract

mentioning

confidence: 99%

Evaluation of intramitochondrial ATP levels identifies G0/G1 switch gene 2 as a positive regulator of oxidative phosphorylation

Kioka¹,

Kato²,

Fujikawa

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

show abstract

“…Furthermore, specific proteins have been found to mediate interactions between specific pairs of respiratory complexes, and functionally removing these proteins prevents the relevant supercomplexes from forming (11)(12)(13)(14). Thus, structural associations between membrane-bound respiratory complexes are increasingly accepted.…”

mentioning

confidence: 99%

Kinetic evidence against partitioning of the ubiquinone pool and the catalytic relevance of respiratory-chain supercomplexes

Blaza

Serreli

Jones

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

163

126

View full text Add to dashboard Cite

In mitochondria, four respiratory-chain complexes drive oxidative phosphorylation by sustaining a proton-motive force across the inner membrane that is used to synthesize ATP. The question of how the densely packed proteins of the inner membrane are organized to optimize structure and function has returned to prominence with the characterization of respiratory-chain supercomplexes. Supercomplexes are increasingly accepted structural entities, but their functional and catalytic advantages are disputed. Notably, substrate "channeling" between the enzymes in supercomplexes has been proposed to confer a kinetic advantage, relative to the rate provided by a freely accessible, common substrate pool. Here, we focus on the mitochondrial ubiquinone/ubiquinol pool. We formulate and test three conceptually simple predictions of the behavior of the mammalian respiratory chain that depend on whether channeling in supercomplexes is kinetically important, and on whether the ubiquinone pool is partitioned between pathways. Our spectroscopic and kinetic experiments demonstrate how the metabolic pathways for NADH and succinate oxidation communicate and catalyze via a single, universally accessible ubiquinone/ubiquinol pool that is not partitioned or channeled. We reevaluate the major piece of contrary evidence from flux control analysis and find that the conclusion of substrate channeling arises from the particular behavior of a single inhibitor; we explain why different inhibitors behave differently and show that a robust flux control analysis provides no evidence for channeling. Finally, we discuss how the formation of respiratory-chain supercomplexes may confer alternative advantages on energy-converting membranes.supercomplex | respirasome | mitochondria | respiratory chain | ubiquinone C ontemporary models for the organization of respiratorychain complexes in energy-transducing membranes range from the fluid model to the respirasome model. In the fluid model each complex is a free and independent entity, and substrates exchange freely between enzymes through common ubiquinone/ubiquinol (Q) and cytochrome c ox /c red (cyt c) pools (1-3). In the respirasome model the complexes are assembled into units that contain everything required for catalysis; substrates are channeled between enzymes within the respirasome, not exchanged with external pools (4, 5). Intermediate models, in which some enzymes are free and some assembled into multienzyme supercomplexes, or in which supercomplexes are assembled and disassembled in response to changing conditions, are increasingly considered a realistic combination of these two extremes (6).Structural evidence for respiratory-chain supercomplexes, initiated by observations by blue native PAGE analyses of mammalian mitochondria (4, 7), has culminated in electron microscopy data that revealed the arrangement of complexes I, III, and IV in a particular class of isolated supercomplex assembly (8, 9); respiratory-chain supercomplexes have also been observed (at lower resolution) in the membrane (10...

show abstract

“…Recently, respiratory supercomplex factor 1 (Rcf1) and its homologue Rcf2 have been identified in yeast as factors required for the normal assembly and complete enzymatic activity of complex IV [19][20][21] . Rcf1 and Rcf2 are both required for complete complex IV assembly and enzyme activity.…”

mentioning

confidence: 99%

A stabilizing factor for mitochondrial respiratory supercomplex assembly regulates energy metabolism in muscle

et al. 2013

View full text Add to dashboard Cite

The mitochondrial respiratory chain is essential for oxidative phosphorylation and comprises multiple complexes, including cytochrome c oxidase, assembled in macromolecular supercomplexes. Little is known about factors that contribute to supercomplex organization. Here we identify COX7RP as a factor that promotes supercomplex assembly. Cox7rp-knockout mice exhibit decreased muscular activity and heat production failure in the cold due to reduced COX activity. In contrast, COX7RP-transgenic mice exhibit increased exercise performance with increased cytochrome c oxidase activity. Two-dimensional blue native electrophoresis reveals that COX7RP is a key molecule that promotes assembly of the III 2 /IV n supercomplex with complex I. Our study identified COX7RP as a protein that functions in I/III 2 /IV n supercomplex assembly and is required for full activity of mitochondrial respiration.

show abstract

Identification of a Protein Mediating Respiratory Supercomplex Stability

Cited by 199 publications

References 37 publications

Evaluation of intramitochondrial ATP levels identifies G0/G1 switch gene 2 as a positive regulator of oxidative phosphorylation

Evaluation of intramitochondrial ATP levels identifies G0/G1 switch gene 2 as a positive regulator of oxidative phosphorylation

Kinetic evidence against partitioning of the ubiquinone pool and the catalytic relevance of respiratory-chain supercomplexes

A stabilizing factor for mitochondrial respiratory supercomplex assembly regulates energy metabolism in muscle

Contact Info

Product

Resources

About