Bioenergetics

  • Article
    | Open Access

    Photosynthetic Complex I (PS-CI) is proposed to couple ferredoxin oxidation and plastoquinone reduction to proton pumping across thylakoid membranes. Here the authors determine the reduction potentials of the iron-sulphur clusters of PS-CI and thus the bioenergetics of the electron transfer relay.

    • Katherine H. Richardson
    • , John J. Wright
    •  & Maxie M. Roessler
  • Article
    | Open Access

    M. tuberculosis cytochrome bd oxidase is of interest as a TB drug target. Here, the authors present the 2.5 Å cryo-EM structure of M. tuberculosis cytochrome bd oxidase and identify a disulfide bond within the canonical quinol binding and oxidation domain (Q-loop) and a menaquinone-9 binding site at heme b595.

    • Schara Safarian
    • , Helen K. Opel-Reading
    •  & Hartmut Michel
  • Article
    | Open Access

    The nature of the mitochondrial permeability transition pore (PTP) is still under debate. Here, through genetically modified F-ATP synthase, the authors show that PTP formation can be mediated by F-ATP synthase or by adenine nucleotide translocator, suggesting the existence of distinct but related permeability pathways.

    • Andrea Carrer
    • , Ludovica Tommasin
    •  & Paolo Bernardi
  • Article
    | Open Access

    Formulating metabolic networks mathematically can help researchers study metabolic diseases and optimize the production of industrially important molecules. Here, the authors propose a framework that allows to model eukaryotic metabolism considering gene expression and thermodynamic constraints.

    • Omid Oftadeh
    • , Pierre Salvy
    •  & Vassily Hatzimanikatis
  • Article
    | Open Access

    Evolution selects for the fittest but must operate within the realm of the physically possible. Here, the authors present a theoretical framework that allows them to explore how ten abiotic constraints can shape the operation, regulation, and adaptation of metabolism in E. coli.

    • Amir Akbari
    • , James T. Yurkovich
    •  & Bernhard O. Palsson
  • Article
    | Open Access

    The high potential iron-sulfur (HiPIP) proteins are direct electron donors to the light-harvesting-reaction center complexes (LH1-RC) in photosynthetic β- and γ-Proteobacteria. Here, the authors present the 2.9 Å crystal structure of the HiPIP-bound LH1-RC complex from the thermophilic purple sulfur bacterium Thermochromatium tepidum and discuss mechanistic implications for the electron transfer pathway.

    • Tomoaki Kawakami
    • , Long-Jiang Yu
    •  & Zheng-Yu Wang-Otomo
  • Article
    | Open Access

    Phytoplankton account for a large proportion of global primary production and comprise a number of phylogenetically distinct lineages. Here, Uwizeye et al. use FIB-SEM to study ultrastructural plasticity of 7 distinct taxa and describe how subcellular organisation is linked to energy metabolism.

    • Clarisse Uwizeye
    • , Johan Decelle
    •  & Giovanni Finazzi
  • Article
    | Open Access

    Reactive oxygen species (ROS) production by reverse electron transfer (RET) through complex I is thought to cause tissue damage from heart attacks. Here, the authors combine in vivo work with biochemical and cryo-EM analyses to characterize the effects of a P25L mutation in the ND6 subunit of mitochondrial complex I. They observe that this mutation does not affect oxidative phosphorylation but renders complex I unable to generate ROS by RET: ND6-P25L mice are protected against cardiac ischaemia–reperfusion injury, thus providing evidence for the proposed role of ROS production in myocardial infarction.

    • Zhan Yin
    • , Nils Burger
    •  & Judy Hirst
  • Article
    | Open Access

    Respiratory complex I plays a key role in energy metabolism. Cryo-EM structure of a mutant accessory subunit LYRM6 from the yeast Yarrowia lipolytica and molecular dynamics simulations reveal conformational changes at the interface between LYRM6 and subunit ND3, propagated further into the complex. These findings offer insight into the mechanism of proton pumping by respiratory complex I.

    • Etienne Galemou Yoga
    • , Kristian Parey
    •  & Heike Angerer
  • Article
    | Open Access

    The respiratory complex I (NADH:ubiquinone oxidoreductase) is a large redox-driven proton pump that initiates respiration in mitochondria. Here, the authors present the 3.0 Å cryo-EM structure of complex I from mouse heart mitochondria with the ubiquinone-analogue inhibitor piericidin A bound in the active site and with kinetic measurements and MD simulations they further show that this inhibitor acts competitively against the native ubiquinone-10 substrate.

    • Hannah R. Bridges
    • , Justin G. Fedor
    •  & Judy Hirst
  • Article
    | Open Access

    Diatoms are marine algae with an important role in global photosynthetic carbon fixation. Here, the authors present the 2.38 Å cryo-EM structure of photosystem I (PSI) in complex with its 24 fucoxanthin chlorophyll a/c-binding (FCPI) antenna proteins from the diatom Chaetoceros gracilis, which provides mechanistic insights into light-energy harvesting, transfer and quenching of the PSI-FCPI supercomplex.

    • Caizhe Xu
    • , Xiong Pi
    •  & Jian-Ren Shen
  • Article
    | Open Access

    ATP drives most cellular processes, although ATP production and consumption levels during mitosis remain unreported. Here, the authors combine metabolic measurements and modeling to quantify ATP levels and synthesis dynamics, revealing that ATP synthesis and consumption are lowered during mitosis.

    • Joon Ho Kang
    • , Georgios Katsikis
    •  & Teemu P. Miettinen
  • Article
    | Open Access

    The pyruvate dehydrogenase complex (PDC) is a multienzyme complex connecting glycolysis to mitochondrial oxidation of pyruvate. Cryo-EM analysis of PDC from Neurospora crassa reveals localization of fungi-specific protein X (PX) and confirms that it functions like the mammalian E3BP, recruiting the E3 component of PDC.

    • B. O. Forsberg
    • , S. Aibara
    •  & E. Lindahl
  • Article
    | Open Access

    Complex I (NADH:ubiquinone oxidoreductase) is the first enzyme of the respiratory chain in bacteria and mitochondria. Here, the authors present cryo-EM and crystal structures of T. thermophilus complex I in different conformational states and further analyse them by Normal Mode Analysis and molecular dynamics simulations and conclude that quinone redox reactions are important for the coupling mechanism of complex I.

    • Javier Gutiérrez-Fernández
    • , Karol Kaszuba
    •  & Leonid A. Sazanov
  • Article
    | Open Access

    F1Fo ATP synthase consists of two coupled rotary molecular motors: the soluble ATPase F1 and the transmembrane Fo. Here, the authors present cryo-EM structures of E. coli ATP synthase in four discrete rotational sub-states at 3.1-3.4 Å resolution and observe a rotary sub-step of the Fo motor cring that reveals the mechanism of elastic coupling between the two rotary motors, which is essential for effective ATP synthesis.

    • Meghna Sobti
    • , James L. Walshe
    •  & Alastair G. Stewart
  • Article
    | Open Access

    Acyl-acyl carrier protein reductase (AAR) and aldehyde deformylating oxygenase (ADO) are the two enzymes in a cyanobacterial alkane biosynthesis pathway that is of interest for biofuel production. Here the authors provide insights into the catalytic mechanisms of AAR and the coupling between the two enzymes by determining the crystal structures of AAR alone and three AAR–ADO complexes with various bound ligands.

    • Yu Gao
    • , Hongmei Zhang
    •  & Mei Li
  • Article
    | Open Access

    The molecular identity of the mitochondrial megachannel (MMC)/permeability transition pore (PTP), a key effector of cell death, remains controversial. Here authors demonstrate that the membrane embedded bovine F-ATP synthase elicits Ca2 + -dependent currents matching those of the MMC/PTP.

    • Andrea Urbani
    • , Valentina Giorgio
    •  & Paolo Bernardi
  • Article
    | Open Access

    Extracellular electron uptake (EEU) is the ability of microbes to take up electrons from solid-phase conductive substances such as metal oxides. Here, Guzman et al. show that electrons enter the photosynthetic electron transport chain and are used for CO2 fixation during EEU in a phototrophic bacterium.

    • Michael S. Guzman
    • , Karthikeyan Rengasamy
    •  & Arpita Bose
  • Article
    | Open Access

    Assessing biological circuit connections in single cells has been intractable due to lack of appropriate tools. Here, Bleck et al. develop a method to assess mitochondrial network connectivity in muscle cells and observe clear differences consistent with differing energy requirements.

    • Christopher K. E. Bleck
    • , Yuho Kim
    •  & Brian Glancy
  • Article
    | Open Access

    Cytochrome c oxidase (CytcO) is the last enzyme of the electron transport chain, but how the electrochemical membrane potential affects CytcO is unclear. Here the authors show that proton uptake to the catalytic site of CytcO and presumably proton translocation was impaired by the potential, but electron transfer was not affected.

    • Markus L. Björck
    •  & Peter Brzezinski
  • Article
    | Open Access

    Biologically ### produced electrical currents and hydrogen are new energy sources. Here, the authors find that low presser microfluidizer treatment produced cyanobacterium that can utilize electrons from respiratory and photosynthesis to promote current and hydrogen generation, without the addition of exogenous electron mediators.

    • Gadiel Saper
    • , Dan Kallmann
    •  & Noam Adir
  • Article
    | Open Access

    Some prokaryotes use alternative respiratory chain complexes, such as the alternative complex III (ACIII), to generate energy. Here authors provide the cryoEM structure of ACIII from Rhodothermus marinus which shows the arrangement of cofactors and provides insights into the mechanism for energy transduction.

    • Joana S. Sousa
    • , Filipa Calisto
    •  & Manuela M. Pereira
  • Article
    | Open Access

    Water splitting during photosynthesis results in the combination of two oxygen atoms to form O2. Here, based on computational simulations, the authors develop a possible mechanism for this reaction, which is different from the mechanisms previous studies have suggested.

    • Keisuke Kawashima
    • , Tomohiro Takaoka
    •  & Hiroshi Ishikita
  • Article
    | Open Access

    Sunlight harvesting and redirection is a promising concept for sustainable energy conversion, however losses have hindered progress. Here the authors construct a simple biomimetic device which minimises losses by using reservoirs of randomly-oriented dyes to funnel energy onto individual emitting parallel acceptors.

    • Alexander Pieper
    • , Manuel Hohgardt
    •  & Peter Jomo Walla
  • Article
    | Open Access

    H+-ATPases employ a rotary catalytic mechanism to couple ATP synthesis/hydrolysis with proton translocation through the membrane. Here, the authors use high-resolution cryoEM to characterize three rotational states of a bacterial H+-ATPase, providing a more detailed model of its catalytic mechanism.

    • Atsuko Nakanishi
    • , Jun-ichi Kishikawa
    •  & Ken Yokoyama
  • Article
    | Open Access

    Carotenoids can dissipate excess energy captured by photosynthetic light-harvesting complexes to prevent photodamage. Here, via spectroscopic and in silico approaches, Liguori et al. resolve different carotenoid dark states and propose conformational changes that permit them to act as either energy donors or quenchers.

    • Nicoletta Liguori
    • , Pengqi Xu
    •  & Roberta Croce
  • Article
    | Open Access

    Devices that harness electron flow from photosynthetic organisms generally compromise host photosynthesis. Here, the authors show that, by redesigning the QAsite of Photosystem II, it is possible to reroute electrons to an exogenous quinone while maintaining endogenous photosynthetic electron transfer in a green alga.

    • Han-Yi Fu
    • , Daniel Picot
    •  & Francis-André Wollman
  • Article
    | Open Access

    Photosynthesis uses only a limited range of solar radiation. Here, Graysonet al. genetically incorporated the yellow fluorescent protein (YFP) chromophore into a bacterial photosystem, and show that energy harvested by reaction centre–YFP complexes can augment photosynthesis in vivo.

    • Katie J. Grayson
    • , Kaitlyn M. Faries
    •  & C. Neil Hunter
  • Article
    | Open Access

    Assembling multiple biological components into synthetic lipid vesicles is a limiting step in the manufacture of biomimetic cell-like structures. Here the authors use fusogenic proteoliposomes of opposite charge for fast assembly of a minimal electron transport chain consisting of F1F0 ATP-synthase and the proton pump bo3-oxidase.

    • Robert R. Ishmukhametov
    • , Aidan N. Russell
    •  & Richard M. Berry
  • Article
    | Open Access

    The availability of crystal structures of photosystem II opens up the possibility of gaining insights into its mechanism. Here, the authors use a computational approach and propose a deprotonation event at O4 followed by long-range proton-transfer along a chain of strongly bonded water molecules.

    • Keisuke Saito
    • , A. William Rutherford
    •  & Hiroshi Ishikita
  • Article
    | Open Access

    Receptor tyrosine kinases are key mediators of cell proliferation that have been implicated in several disease states for which they represent promising drug targets. Here the authors determine the thermodynamic basis for the low propensity of FGFR1 to access the DFG-Phe-out conformation required to bind type-II inhibitors.

    • Tobias Klein
    • , Navratna Vajpai
    •  & Alexander L. Breeze
  • Article
    | Open Access

    Although most protein folding experiments can be explained by a single pathway, theoretical evidence suggests the presence of multiple pathways. Here, the authors resolve this using a combination of force, chemical denaturation and mutagenesis to modulate the flux between parallel pathways.

    • Emily J. Guinn
    • , Bharat Jagannathan
    •  & Susan Marqusee
  • Article |

    Rotary ATPases exhibit similar architecture and mechanism but distinct physiological functions, operating either as ion pumps or ATP synthases. Here the authors report the structure and mechanism of the c-ring from the A. woodiiATP synthase, and suggest an evolutionary path between synthases and pumps through adaptations in this molecular rotor.

    • Doreen Matthies
    • , Wenchang Zhou
    •  & Thomas Meier
  • Article
    | Open Access

    ABC systems are an important class of transporters involved in human pathologies for which the basis for transport remains poorly understood. Here the authors suggest a molecular basis for ATP-powered vectorial peptide export by the human transporter associated with antigen processing (TAP).

    • Nina Grossmann
    • , Ahmet S. Vakkasoglu
    •  & Robert Tampé
  • Article |

    Some biological reactions can require thermodynamically unfavourable electron transfer processes, the occurrence of which are not yet fully understood. Here, the authors provide the structural basis of energy transduction during the reductive activation of B12-dependent methyltransferases.

    • Sandra E. Hennig
    • , Sebastian Goetzl
    •  & Holger Dobbek
  • Article
    | Open Access

    The oxygen-evolving complex of photosystem II converts water into oxygen during photosynthesis, but how this process occurs is not yet fully understood. Here, the authors use modified complexes with reduced reaction rates to study the process of oxygen evolution in more detail.

    • Håkan Nilsson
    • , Fabrice Rappaport
    •  & Johannes Messinger
  • Article
    | Open Access

    Cofactor-mediated energy and electron transfer in photosystem II occurs preferentially through one branch of the reaction centre, despite there being a symmetric path available. Here, the authors use computational methods to determine the influence of protein conformation on this selectivity.

    • Lu Zhang
    • , Daniel-Adriano Silva
    •  & Xuhui Huang
  • Article |

    Incomplete oxidation of fuels is a common problem in enzymatic fuel cells and it leads to low energy densities. Zhu et al. report the complete oxidation of sugar in an enzymatic fuel cell through a synthetic enzymatic pathway, which exhibits higher energy densities than lithium-ion batteries.

    • Zhiguang Zhu
    • , Tsz Kin Tam
    •  & Y. -H. Percival Zhang
  • Article |

    The mitochondrial calcium uniporter supports oxidative phosphorylation in mammals; however, it is also present in blood-stage trypanosomes, which lack a functional respiratory chain. Huang et al. show that the mitochondrial calcium uniporter is essential for blood-stage survival and metabolism in Trypanosoma brucei.

    • Guozhong Huang
    • , Anibal E. Vercesi
    •  & Roberto Docampo
  • Article |

    Microbial fuels cells present a way of generating electricity using the natural metabolism of microorganisms. Here the authors carry out single-cell current measurements ofGeobacter sulfurreducensDL-1 to determine the upper limits of microbial fuel cell performance.

    • Xiaocheng Jiang
    • , Jinsong Hu
    •  & Justin C. Biffinger
  • Article
    | Open Access

    The switch from linear to cyclic electron flow has long been thought to rely on the migration of antenna proteins from Photosystem II to Photosystem I. Takahashi et al. report that this is not the case and that cyclic electron flow is tuned by the intrachloroplastic redox power.

    • Hiroko Takahashi
    • , Sophie Clowez
    •  & Fabrice Rappaport