The protonmotive Q cycle. Energy transduction by coupling of proton translocation to electron transfer by the cytochrome bc1 complex.

Trumpower, Bernard L.

doi:10.1016/s0021-9258(19)38410-8

Cited by 518 publications

(115 citation statements)

References 34 publications

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“…i'm 1 a periplasmic quinol oxidation (Q.) site and a cytoplasmic quinone reduction (Qi) site, thought to function in a Q-cycle mechanism [48]. Because subunit IV is a possible Q-binding protein [8,19], and the Q-binding domain is believed to be localized within amino acid residues 81-90, the topological results presented here suggest that this region is located on the cytoplasmic side of the ICM.…”

Section: Discussionmentioning

confidence: 89%

Topological organization of the Rieske iron-sulphur protein and subunit IV in the cytochrome bc1 complex of Rhodobacter sphaeroides

Niederman

1995

Biochemical Journal

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The ubiquinol-cytochrome c2 oxidoreductases (cytochrome bc1 complex) of Rhodobacter sphaeroides contains highly conserved cytochrome b, cytochrome c1 and Rieske FeS subunits, as well as a unique 14 kDa polypeptide, designated as subunit IV, thought to function as a ubiquinol-binding protein [Yu and Yu (1991) Biochemistry 30, 4934-4939]. As the topology of subunit IV is unknown and that of the FeS subunit remains a matter of debate, both the inner (cytoplasmic) and outer (periplasmic) surfaces of the intracytoplasmic membrane (ICM) were digested with proteinase K, and cleavage products were identified by immunoblotting. In uniformly oriented chromatophore vesicles (inner ICM surface exposed), fragments of approx. 4 and 1 kDa were removed from subunit IV and the FeS protein respectively. Neither subunit IV nor the FeS protein was cleaved from the outer ICM surface as exposed in osmotically protected spheroplasts or as presented to proteinase K after microencapsulation of the protease in unilamellar liposomes and fusion of these structures to chromatophore vesicles. Studies with the isolated bc1 complex, however, suggested that the C-terminal domain of the Rieske FeS, thought to reside on the periplasmic side of the ICM, was resistant to proteinase K. Overall, these results suggest a single N-terminal transmembrane helix for the FeS protein, with exposure of the N-terminus to the cytoplasm and an orientation in which a major, N-terminal portion of subunit IV is located in the cytoplasm with the predicted C-terminal transmembrane domain anchoring this polypeptide to the membrane.

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Section: Discussionmentioning

confidence: 89%

Topological organization of the Rieske iron-sulphur protein and subunit IV in the cytochrome bc1 complex of Rhodobacter sphaeroides

Niederman

1995

Biochemical Journal

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“…The mechanism by which the cyt bc 1 carries out its ET-coupled proton translocation is known as the Q-cycle mechanism (Fig. 1) (7). This mechanism requires a quinol oxidation site (Q o or Q P site) near the electrochemically-positive side of the membrane and a quinone reduction site (Q i or Q N site) near the negative side of the membrane.…”

mentioning

confidence: 99%

Crystal structure of bacterial cytochrome bc1 in complex with azoxystrobin reveals a conformational switch of the Rieske iron–sulfur protein subunit

Esser

Zhou

et al. 2019

Journal of Biological Chemistry

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“…In hyperglycemia, the enhanced glucose flux though glycolysis results in more glucose-derived pyruvate being oxidized in the mitochondrial tricarboxylic acid (TCA) cycle, increasing the flux of electron donors into the electron transport chain and the voltage gradient across the inner mitochondrial membrane. When a critical point of the voltage gradient is reached, the electron transfer inside Complex III is blocked [37], causing the electrons to back up to coenzyme Q, which transfers the electrons one at a time to O 2 , thereby generating superoxide [38].…”

Section: Figurementioning

confidence: 99%

Diabetic Complications and Oxidative Stress: A 20-Year Voyage Back in Time and Back to the Future

et al. 2021

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Twenty years have passed since Brownlee and colleagues proposed a single unifying mechanism for diabetic complications, introducing a turning point in this field of research. For the first time, reactive oxygen species (ROS) were identified as the causal link between hyperglycemia and four seemingly independent pathways that are involved in the pathogenesis of diabetes-associated vascular disease. Before and after this milestone in diabetes research, hundreds of articles describe a role for ROS, but the failure of clinical trials to demonstrate antioxidant benefits and some recent experimental studies showing that ROS are dispensable for the pathogenesis of diabetic complications call for time to reflect. This twenty-year journey focuses on the most relevant literature regarding the main sources of ROS generation in diabetes and their role in the pathogenesis of cell dysfunction and diabetic complications. To identify future research directions, this review discusses the evidence in favor and against oxidative stress as an initial event in the cellular biochemical abnormalities induced by hyperglycemia. It also explores possible alternative mechanisms, including carbonyl stress and the Warburg effect, linking glucose and lipid excess, mitochondrial dysfunction, and the activation of alternative pathways of glucose metabolism leading to vascular cell injury and inflammation.

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The protonmotive Q cycle. Energy transduction by coupling of proton translocation to electron transfer by the cytochrome bc1 complex.

Cited by 518 publications

References 34 publications

Topological organization of the Rieske iron-sulphur protein and subunit IV in the cytochrome bc1 complex of Rhodobacter sphaeroides

Topological organization of the Rieske iron-sulphur protein and subunit IV in the cytochrome bc1 complex of Rhodobacter sphaeroides

Crystal structure of bacterial cytochrome bc1 in complex with azoxystrobin reveals a conformational switch of the Rieske iron–sulfur protein subunit

Diabetic Complications and Oxidative Stress: A 20-Year Voyage Back in Time and Back to the Future

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