Dual Mutations Reveal Interactions Between Components of Oxidative Phosphorylation in Kluyveromyces lactis

Genetics ◽  
2001 ◽  
Vol 159 (3) ◽  
pp. 929-938
Author(s):  
G D Clark-Walker ◽  
X J Chen
Keyword(s):  
Electron Transport ◽  
Oxidative Phosphorylation ◽  
Atp Synthase ◽  
Kluyveromyces Lactis ◽  
Mitochondrial Protein ◽  
Proton Pumping ◽  
Nuclear Genes ◽  
Suppressor Activity ◽  
Inner Membrane ◽  
Atp Production

Abstract Loss of mtDNA or mitochondrial protein synthesis cannot be tolerated by wild-type Kluyveromyces lactis. The mitochondrial function responsible for ρ0-lethality has been identified by disruption of nuclear genes encoding electron transport and F0-ATP synthase components of oxidative phosphorylation. Sporulation of diploid strains heterozygous for disruptions in genes for the two components of oxidative phosphorylation results in the formation of nonviable spores inferred to contain both disruptions. Lethality of spores is thought to result from absence of a transmembrane potential, ΔΨ, across the mitochondrial inner membrane due to lack of proton pumping by the electron transport chain or reversal of F1F0-ATP synthase. Synergistic lethality, caused by disruption of nuclear genes, or ρ0-lethality can be suppressed by the atp2.1 mutation in the β-subunit of F1-ATPase. Suppression is viewed as occurring by an increased hydrolysis of ATP by mutant F1, allowing sufficient electrogenic exchange by the translocase of ADP in the matrix for ATP in the cytosol to maintain ΔΨ. In addition, lethality of haploid strains with a disruption of AAC encoding the ADP/ATP translocase can be suppressed by atp2.1. In this case suppression is considered to occur by mutant F1 acting in the forward direction to partially uncouple ATP production, thereby stimulating respiration and relieving detrimental hyperpolarization of the inner membrane. Participation of the ADP/ATP translocase in suppression of ρ0-lethality is supported by the observation that disruption of AAC abolishes suppressor activity of atp2.1.

scholarly journals Kinetic coupling of the respiratory chain with ATP synthase, but not proton gradients, drives ATP production in cristae membranes

2020 ◽  
Vol 117 (5) ◽  
pp. 2412-2421 ◽  
Author(s):  
Alexandra Toth ◽  
Axel Meyrat ◽  
Stefan Stoldt ◽  
Ricardo Santiago ◽  
Dirk Wenzel ◽  
...  
Keyword(s):  
Oxidative Phosphorylation ◽  
Atp Synthase ◽  
Atp Synthesis ◽  
Proton Pumping ◽  
Yeast Cells ◽  
Synthesis Rate ◽  
Proton Gradients ◽  
Inner Membrane ◽  
Ph Values ◽  
Kinetic Coupling

Mitochondria have a characteristic ultrastructure with invaginations of the inner membrane called cristae that contain the protein complexes of the oxidative phosphorylation system. How this particular morphology of the respiratory membrane impacts energy conversion is currently unknown. One proposed role of cristae formation is to facilitate the establishment of local proton gradients to fuel ATP synthesis. Here, we determined the local pH values at defined sublocations within mitochondria of respiring yeast cells by fusing a pH-sensitive GFP to proteins residing in different mitochondrial subcompartments. Only a small proton gradient was detected over the inner membrane in wild type or cristae-lacking cells. Conversely, the obtained pH values did barely permit ATP synthesis in a reconstituted system containing purified yeast F1F0 ATP synthase, although, thermodynamically, a sufficiently high driving force was applied. At higher driving forces, where robust ATP synthesis was observed, a P-side pH value of 6 increased the ATP synthesis rate 3-fold compared to pH 7. In contrast, when ATP synthase was coreconstituted with an active proton-translocating cytochrome oxidase, ATP synthesis readily occurred at the measured, physiological pH values. Our study thus reveals that the morphology of the inner membrane does not influence the subcompartmental pH values and is not necessary for robust oxidative phosphorylation in mitochondria. Instead, it is likely that the dense packing of the oxidative phosphorylation complexes in the cristae membranes assists kinetic coupling between proton pumping and ATP synthesis.

scholarly journals ATP Synthase: Structure, Function and Inhibition

2019 ◽  
Vol 10 (1) ◽  
pp. 1-10 ◽  
Author(s):  
Prashant Neupane ◽  
Sudina Bhuju ◽  
Nita Thapa ◽  
Hitesh Kumar Bhattarai
Keyword(s):  
Electron Transport ◽  
Oxidative Phosphorylation ◽  
Structure Function ◽  
Atp Synthase ◽  
Atp Synthesis ◽  
Living Cells ◽  
Proton Gradient ◽  
Subunit Structure ◽  
Inner Membrane ◽  
And Function

AbstractOxidative phosphorylation is carried out by five complexes, which are the sites for electron transport and ATP synthesis. Among those, Complex V (also known as the F1F0 ATP Synthase or ATPase) is responsible for the generation of ATP through phosphorylation of ADP by using electrochemical energy generated by proton gradient across the inner membrane of mitochondria. A multi subunit structure that works like a pump functions along the proton gradient across the membranes which not only results in ATP synthesis and breakdown, but also facilitates electron transport. Since ATP is the major energy currency in all living cells, its synthesis and function have widely been studied over the last few decades uncovering several aspects of ATP synthase. This review intends to summarize the structure, function and inhibition of the ATP synthase.

scholarly journals The ATP Synthase Deficiency in Human Diseases

Life ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 325
Author(s):  
Chiara Galber ◽  
Stefania Carissimi ◽  
Alessandra Baracca ◽  
Valentina Giorgio
Keyword(s):  
Oxidative Phosphorylation ◽  
Atp Synthase ◽  
Mitochondrial Protein ◽  
High Energy ◽  
Neurocognitive Disorders ◽  
Human Diseases ◽  
Age Related ◽  
Muscle Tissues ◽  
Mitochondrial Atp Synthase ◽  
Genes Encoding

Human diseases range from gene-associated to gene-non-associated disorders, including age-related diseases, neurodegenerative, neuromuscular, cardiovascular, diabetic diseases, neurocognitive disorders and cancer. Mitochondria participate to the cascades of pathogenic events leading to the onset and progression of these diseases independently of their association to mutations of genes encoding mitochondrial protein. Under physiological conditions, the mitochondrial ATP synthase provides the most energy of the cell via the oxidative phosphorylation. Alterations of oxidative phosphorylation mainly affect the tissues characterized by a high-energy metabolism, such as nervous, cardiac and skeletal muscle tissues. In this review, we focus on human diseases caused by altered expressions of ATP synthase genes of both mitochondrial and nuclear origin. Moreover, we describe the contribution of ATP synthase to the pathophysiological mechanisms of other human diseases such as cardiovascular, neurodegenerative diseases or neurocognitive disorders.

scholarly journals Senescence-associated changes in respiration and oxidative phosphorylation in primary human fibroblasts

2004 ◽  
Vol 380 (3) ◽  
pp. 919-928 ◽  
Author(s):  
Eveline HUTTER ◽  
Kathrin RENNER ◽  
Gerald PFISTER ◽  
Petra STÖCKL ◽  
Pidder JANSEN-DÜRR ◽  
...  
Keyword(s):  
Electron Transport ◽  
Oxidative Phosphorylation ◽  
Replicative Senescence ◽  
Citrate Synthase ◽  
Human Fibroblasts ◽  
Respiratory Control ◽  
Compensatory Mechanisms ◽  
Intact Cells ◽  
Atp Production ◽  
Human Diploid Fibroblasts

Limitation of lifespan in replicative senescence is related to oxidative stress, which is probably both the cause and consequence of impaired mitochondrial respiratory function. The respiration of senescent human diploid fibroblasts was analysed by highresolution respirometry. To rule out cell-cycle effects, proliferating and growth-arrested young fibroblasts were used as controls. Uncoupled respiration, as normalized to citrate synthase activity, remained unchanged, reflecting a constant capacity of the respiratory chain. Oligomycin-inhibited respiration, however, was significantly increased in mitochondria of senescent cells, indicating a lower coupling of electron transport with phosphorylation. In contrast, growth-arrested young fibroblasts exhibited a higher coupling state compared with proliferating controls. In intact cells, partial uncoupling may lead to either decreased oxidative ATP production or a compensatory increase in routine respiration. To distinguish between these alternatives, we subtracted oligomycin-inhibited respiration from routine respiration, which allowed us to determine the part of respiratory activity coupled with ATP production. Despite substantial differences in the respiratory control ratio, ranging from 4 to 11 in the different experimental groups, a fixed proportion of respiratory capacity was maintained for coupled oxidative phosphorylation in all the experimental groups. This finding indicates that the senescent cells fully compensate for increased proton leakage by enhanced electron-transport activity in the routine state. These results provide a new insight into age-associated defects in mitochondrial function and compensatory mechanisms in intact cells.

scholarly journals Evidence of Oxidative Phosphorylation in Zebrafish Photoreceptor Outer Segments at Different Larval Stages

2018 ◽  
Vol 66 (7) ◽  
pp. 497-509 ◽  
Author(s):  
Daniela Calzia ◽  
Greta Garbarino ◽  
Federico Caicci ◽  
Mario Pestarino ◽  
Lucia Manni ◽  
...  
Keyword(s):  
Oxidative Phosphorylation ◽  
Atp Synthase ◽  
Aerobic Metabolism ◽  
Respiratory Chain Complexes ◽  
Atp Production ◽  
Photoreceptor Outer Segments ◽  
Larval Stages ◽  
Outer Segments ◽  
Chain Complexes ◽  
Transmission Electron

Summary Previous studies on purified bovine rod outer segments (OS) disks pointed to Oxidative Phosphorylation (OXPHOS) as being the most likely mechanism involved in ATP production, as yet not fully understood, to support the first phototransduction steps. Bovine and murine rod OS disks, devoid of mitochondria, would house respiratory chain complexes I to IV and ATP synthase, similar to mitochondria. Zebrafish ( Danio rerio) is a well-suited animal model to study vertebrate embryogenesis as well as the retina, morphologically and functionally similar to its human counterpart. The present article reports fluorescence and Transmission Electron Microscopy colocalization analyses of respiratory complexes I and IV and ATP synthase with zpr3, the rod OS marker, in adult and larval zebrafish retinas. MitoTracker Deep Red 633 staining and assays of complexes I and III–IV activity suggest that those proteins are active in OS. Results show that an extramitochondrial aerobic metabolism is active in the zebrafish OS at 4 and 10 days of larval development, as well as in adults, suggesting that it is probably maintained during embryogenesis. Data support the hypothesis of an extramitochondrial aerobic metabolism in the OS of zebrafish.

The efficiency and plasticity of mitochondrial energy transduction

2005 ◽  
Vol 33 (5) ◽  
pp. 897-904 ◽  
Author(s):  
M.D. Brand
Keyword(s):  
Electron Transport ◽  
Atp Synthase ◽  
Electron Transport Chain ◽  
Uncoupling Protein ◽  
Coupling Efficiency ◽  
Energy Transduction ◽  
Proton Pumping ◽  
Complex Iii ◽  
Proton Pumps ◽  
Transport Chain

Since it was first realized that biological energy transduction involves oxygen and ATP, opinions about the amount of ATP made per oxygen consumed have continually evolved. The coupling efficiency is crucial because it constrains mechanistic models of the electron-transport chain and ATP synthase, and underpins the physiology and ecology of how organisms prosper in a thermodynamically hostile environment. Mechanistically, we have a good model of proton pumping by complex III of the electron-transport chain and a reasonable understanding of complex IV and the ATP synthase, but remain ignorant about complex I. Energy transduction is plastic: coupling efficiency can vary. Whether this occurs physiologically by molecular slipping in the proton pumps remains controversial. However, the membrane clearly leaks protons, decreasing the energy funnelled into ATP synthesis. Up to 20% of the basal metabolic rate may be used to drive this basal leak. In addition, UCP1 (uncoupling protein 1) is used in specialized tissues to uncouple oxidative phosphorylation, causing adaptive thermogenesis. Other UCPs can also uncouple, but are tightly regulated; they may function to decrease coupling efficiency and so attenuate mitochondrial radical production. UCPs may also integrate inputs from different fuels in pancreatic β-cells and modulate insulin secretion. They are exciting potential targets for treatment of obesity, cachexia, aging and diabetes.

scholarly journals Evolution of Oxidative Phosphorylation (OXPHOS) Genes Reflecting the Evolutionary and Life Histories of Fig Wasps (Hymenoptera, Chalcidoidea)

Genes ◽  
2020 ◽  
Vol 11 (11) ◽  
pp. 1353
Author(s):  
Yi Zhou ◽  
Dawei Huang ◽  
Zhaozhe Xin ◽  
Jinhua Xiao
Keyword(s):  
Amino Acid ◽  
Oxidative Phosphorylation ◽  
Amino Acid Substitution ◽  
Life Histories ◽  
Gene Evolution ◽  
Mitochondrial Protein ◽  
Single Copy ◽  
Fig Wasps ◽  
Atp Production ◽  
High Amino Acid

Fig wasps are a peculiar group of insects which, for millions of years, have inhabited the enclosed syconia of fig trees. Considering the relatively closed and dark environment of fig syconia, we hypothesize that the fig wasps’ oxidative phosphorylation (OXPHOS) pathway, which is the main oxygen consumption and adenosine triphosphate (ATP) production system, may have adaptively evolved. In this study, we manually annotated the OXPHOS genes of 11 species of fig wasps, and compared the evolutionary patterns of OXPHOS genes for six pollinators and five non-pollinators. Thirteen mitochondrial protein-coding genes and 30 nuclear-coding single-copy orthologous genes were used to analyze the amino acid substitution rate and natural selection. The results showed high amino acid substitution rates of both mitochondrial and nuclear OXPHOS genes in fig wasps, implying the co-evolution of mitochondrial and nuclear genes. Our results further revealed that the OXPHOS-related genes evolved significantly faster in pollinators than in non-pollinators, and five genes had significant positive selection signals in the pollinator lineage, indicating that OXPHOS genes play an important role in the adaptation of pollinators. This study can help us understand the relationship between gene evolution and environmental adaptation.

scholarly journals Oxidative phosphorylation is required for powering motility and development of the sleeping sickness parasite Trypanosoma brucei within the tsetse fly vector

2021 ◽  
Author(s):  
Caroline E Dewar ◽  
Aitor Casas-Sánchez ◽  
Constentin Dieme ◽  
Aline Crouzols ◽  
Lee Haines ◽  
...  
Keyword(s):  
Oxidative Phosphorylation ◽  
Trypanosoma Brucei ◽  
Atp Synthase ◽  
Sleeping Sickness ◽  
Tsetse Fly ◽  
Tsetse Flies ◽  
Respiratory Chain Complexes ◽  
Atp Production

The single-celled parasite Trypanosoma brucei causes sleeping sickness in humans and nagana in livestock and is transmitted by hematophagous tsetse flies. Lifecycle progression from mammalian bloodstream form to tsetse midgut form and, subsequently, infective salivary gland form depends on complex developmental steps and migration within different fly tissues. As the parasite colonises the glucose-poor insect midgut, its ATP production is thought to depend on activation of mitochondrial amino acid catabolism via oxidative phosphorylation. This process involves respiratory chain complexes and the F1FO-ATP synthase, and it requires protein subunits of these complexes that are encoded in the parasite's mitochondrial DNA (kinetoplast or kDNA). Here we show that a progressive loss of kDNA-encoded functions correlates with an increasingly impaired ability of T. brucei to initiate and complete its development in the tsetse. First, parasites with a mutated F1FO-ATP synthase with a reduced capacity for oxidative phosphorylation can initiate differentiation from bloodstream to insect form, but they are unable to proliferate in vitro. Unexpectedly, these cells can still colonise the tsetse midgut. However, these parasites exhibit a motility defect and are severely impaired in colonising or migrating to subsequent tsetse tissues. Second, parasites with a fully disrupted F1FO-ATP synthase complex that is completely unable to produce ATP by oxidative phosphorylation can still differentiate to the first insect stage in vitro but die within a few days and cannot establish a midgut infection in vivo. Third, mutant parasites lacking kDNA entirely can initiate differentiation but die within 24 h. Together, these three scenarios show that efficient ATP production via oxidative phosphorylation is not essential for initial colonisation of the tsetse vector, but it is required to power trypanosome migration within the fly.

scholarly journals Lichen fungi do not depend on the alga for ATP production

2021 ◽  
Author(s):  
Gulnara Tagirdzhanova ◽  
John McCutcheon ◽  
Toby Spribille
Keyword(s):  
Oxidative Phosphorylation ◽  
Atp Synthase ◽  
Mitochondrial Genomes ◽  
Symbiotic Association ◽  
Mitochondrial Oxidative Phosphorylation ◽  
Gene Encoding ◽  
Apparent Lack ◽  
Atp Production

Lichen fungi live in a symbiotic association with unicellular phototrophs and have no known aposymbiotic stage. A recent study postulated that some of them have lost mitochondrial oxidative phosphorylation and rely on their algal partners for ATP. This claim originated from an apparent lack of ATP9, a gene encoding one subunit of ATP synthase, from a few mitochondrial genomes. Here we show that while these fungi indeed have lost the mitochondrial ATP9, each retain a nuclear copy of this gene. Our analysis reaffirms that lichen fungi produce their own ATP.

scholarly journals Quality control of mitochondrial protein synthesis is required for membrane integrity and cell fitness

2015 ◽  
Vol 211 (2) ◽  
pp. 373-389 ◽  
Author(s):  
Uwe Richter ◽  
Taina Lahtinen ◽  
Paula Marttinen ◽  
Fumi Suomi ◽  
Brendan J. Battersby
Keyword(s):  
Quality Control ◽  
Protein Synthesis ◽  
Oxidative Phosphorylation ◽  
De Novo ◽  
Mitochondrial Protein ◽  
Membrane Integrity ◽  
Mitochondrial Proteins ◽  
Protein Accumulation ◽  
Mitochondrial Protein Synthesis ◽  
Inner Membrane

Mitochondrial ribosomes synthesize a subset of hydrophobic proteins required for assembly of the oxidative phosphorylation complexes. This process requires temporal and spatial coordination and regulation, so quality control of mitochondrial protein synthesis is paramount to maintain proteostasis. We show how impaired turnover of de novo mitochondrial proteins leads to aberrant protein accumulation in the mitochondrial inner membrane. This creates a stress in the inner membrane that progressively dissipates the mitochondrial membrane potential, which in turn stalls mitochondrial protein synthesis and fragments the mitochondrial network. The mitochondrial m-AAA protease subunit AFG3L2 is critical to this surveillance mechanism that we propose acts as a sensor to couple the synthesis of mitochondrial proteins with organelle fitness, thus ensuring coordinated assembly of the oxidative phosphorylation complexes from two sets of ribosomes.

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