253 results found
Varghese F, Kabasakal BV, Cotton CA, et al., 2019, A low-potential terminal oxidase associated with the iron-only nitrogenase from the nitrogen-fixing bacterium Azotobacter vinelandii., J Biol Chem
The biological route for nitrogen gas entering the biosphere is reduction to ammonia by the nitrogenase enzyme, which is inactivated by oxygen. Three types of nitrogenase exist, the least studied of which is the iron-only nitrogenase. The Anf3 protein in the bacterium Rhodobacter capsulatus is essential for diazotrophic (i.e. nitrogen-fixing) growth with the iron-only nitrogenase, but its enzymatic activity and function are unknown. Here, we biochemically and structurally characterize Anf3 from the model diazotrophic bacterium Azotobacter vinelandii. Determining the Anf3 crystal structure to atomic resolution, we observed that it is a dimeric flavocytochrome with an unusually close interaction between the heme and the flavin adenine dinucleotide cofactors. Measuring the reduction potentials by spectroelectrochemical redox titration, we observed values of -420 ± 10 mV and -330 ± 10 mV for the two FAD potentials and -340 ± 1 mV for the heme. We further show that Anf3 accepts electrons from spinach ferredoxin and that Anf3 consumes oxygen without generating superoxide or hydrogen peroxide. We predict that Anf3 protects the iron-only nitrogenase from oxygen inactivation by functioning as an oxidase in respiratory protection, with flavodoxin or ferredoxin as the physiological electron donors.
Takegawa Y, Nakamura M, Nakamura S, et al., 2019, New insights on Chlm function in Photosystem II from site-directed mutants of D1/T179 in Thermosynechococcus elongatus, BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS, Vol: 1860, Pages: 297-309, ISSN: 0005-2728
Zamzam N, Kaucikas M, Nurnberg DJ, et al., 2019, Femtosecond infrared spectroscopy of chlorophyll f-containing photosystem I, PHYSICAL CHEMISTRY CHEMICAL PHYSICS, Vol: 21, Pages: 1224-1234, ISSN: 1463-9076
Cardona T, Rutherford W, 2018, Evolution of photochemical reaction centres: more twists?
The earliest event recorded in the molecular evolution of photosynthesis is the structural and functional specialisation of Type I (ferredoxin-reducing) and Type II (quinone-reducing) reaction centres. Here we point out that the homodimeric Type I reaction centre of Heliobacteria has a Ca2+-binding site with a number of striking parallels to the Mn4CaO5 cluster of cyanobacterial Photosystem II. This structural parallels indicate that water oxidation chemistry originated at the divergence of Type I and Type II reaction centres. We suggests that this divergence was triggered by a structural rearrangement of a core transmembrane helix resulting in a shift of the redox potential of the electron donor side and electron acceptor side at the same time and in the same redox direction.
Kornienko N, Zhang JZ, Sokol K, et al., 2018, Oxygenic photoreactivity in photosystem II studied by rotating ring disk electrochemistry, Journal of the American Chemical Society, ISSN: 1520-5126
Protein film photoelectrochemistry has previously been used to monitor the activity of Photosystem II, the water-plastoquinone photooxidoreductase, but the mechanistic information attainable from a three-electrode setup has remained limited. Here we introduce the four-electrode rotating ring disk electrode technique for quantifying light-driven reaction kinetics and mechanistic pathways in real time at the enzyme-electrode interface. This setup allows us to study photochemical H2O oxidation in Photosystem II and to gain in-depth understanding of pathways that generate reactive oxygen species. The results show that Photosystem II reacts with O2 through two main pathways that both involve a superoxide intermediate to produce H2O2. The first pathway involves the established chlorophyll triplet-mediated formation of singlet oxygen, which is followed by its reduction to superoxide at the electrode surface. The second pathway is specific for the enzyme/electrode interface: an exposed antenna chlorophyll is sufficiently close to the electrode for rapid injection of an electron to form a highly reducing chlorophyll anion, which reacts with O2 in solution to produce O2•-. Incomplete H2O oxidation does not significantly contribute to reactive oxygen formation in our conditions. The rotating ring disk electrode technique allows the chemical reactivity of Photosystem II to be studied electrochemically and opens several avenues for future investigation.
Messant M, Timm S, Fantuzzi A, et al., 2018, Glycolate Induces Redox Tuning Of Photosystem II in Vivo: Study of a Photorespiration Mutant, PLANT PHYSIOLOGY, Vol: 177, Pages: 1277-1285, ISSN: 0032-0889
Nuernberg DJ, Morton J, Santabarbara S, et al., 2018, Photochemistry beyond the red limit in chlorophyll f-containing photosystems, SCIENCE, Vol: 360, Pages: 1210-1213, ISSN: 0036-8075
Boussac A, Ugur I, Marion A, et al., 2018, The low spin - high spin equilibrium in the S-2-state of the water oxidizing enzyme, BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS, Vol: 1859, Pages: 342-356, ISSN: 0005-2728
Zhang JZ, Bombelli P, Sokol KP, et al., 2018, Photoelectrochemistry of Photosystem II &ITin Vitro&IT vs&IT in Vivo&IT, Journal of the American Chemical Society, Vol: 140, Pages: 6-9, ISSN: 1520-5126
Factors governing the photoelectrochemical output of photosynthetic microorganisms are poorly understood, and energy loss may occur due to inefficient electron transfer (ET) processes. Here, we systematically compare the photoelectrochemistry of photosystem II (PSII) protein-films to cyanobacteria biofilms to derive: (i) the losses in light-to-charge conversion efficiencies, (ii) gains in photocatalytic longevity, and (iii) insights into the ET mechanism at the biofilm interface. This study was enabled by the use of hierarchically structured electrodes, which could be tailored for high/stable loadings of PSII core complexes and Synechocystis sp. PCC 6803 cells. The mediated photocurrent densities generated by the biofilm were 2 orders of magnitude lower than those of the protein-film. This was partly attributed to a lower photocatalyst loading as the rate of mediated electron extraction from PSII in vitro is only double that of PSII in vivo. On the other hand, the biofilm exhibited much greater longevity (>5 days) than the protein-film (<6 h), with turnover numbers surpassing those of the protein-film after 2 days. The mechanism of biofilm electrogenesis is suggested to involve an intracellular redox mediator, which is released during light irradiation.
Lohmiller T, Krewald V, Sedoud A, et al., 2017, The First State in the Catalytic Cycle of the Water-Oxidizing Enzyme: Identification of a Water-Derived mu-Hydroxo Bridge, JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, Vol: 139, Pages: 14412-14424, ISSN: 0002-7863
Davis GA, Rutherford AW, Kramer DM, 2017, Hacking the thylakoid proton motive force for improved photosynthesis: modulating ion flux rates that control proton motive force partitioning into Delta psi and Delta pH, PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY B-BIOLOGICAL SCIENCES, Vol: 372, ISSN: 0962-8436
Kornienko N, van Grondelle R, Rutherford AW, et al., 2017, Quantitatively probing photosystem II with a rotating ring disk electrode assembly, 254th National Meeting and Exposition of the American-Chemical-Society (ACS) on Chemistry's Impact on the Global Economy, Publisher: AMER CHEMICAL SOC, ISSN: 0065-7727
Kaucikas M, Nurnberg D, Dorlhiac G, et al., 2017, Femtosecond Visible Transient Absorption Spectroscopy of Chlorophyll f-Containing Photosystem I, BIOPHYSICAL JOURNAL, Vol: 112, Pages: 234-249, ISSN: 0006-3495
Brinkert K, De Causmaecker S, Krieger-Liszkay A, et al., 2016, Bicarbonate-induced redox tuning in Photosystem II for regulation and protection, PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, Vol: 113, Pages: 12144-12149, ISSN: 0027-8424
Davis GA, Kanazawa A, Schoettler MA, et al., 2016, Limitations to photosynthesis by proton motive force-induced photosystem II photodamage, ELIFE, Vol: 5, ISSN: 2050-084X
Brinkert K, Le Formal F, Li X, et al., 2016, Photocurrents from photosystem II in a metal oxide hybrid system: Electron transfer pathways, BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS, Vol: 1857, Pages: 1497-1505, ISSN: 0005-2728
Ugur I, Rutherford AW, Kaila VRI, 2016, Redox-coupled substrate water reorganization in the active site of Photosystem II-The role of calcium in substrate water delivery, BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS, Vol: 1857, Pages: 740-748, ISSN: 0005-2728
MacKellar D, Lieber L, Norman JS, et al., 2016, Streptomyces thermoautotrophicus does not fix nitrogen, SCIENTIFIC REPORTS, Vol: 6, ISSN: 2045-2322
Saito K, Rutherford AW, Ishikita H, 2015, Energetics of proton release on the first oxidation step in the water-oxidizing enzyme, NATURE COMMUNICATIONS, Vol: 6, ISSN: 2041-1723
Mersch D, Lee C-Y, Zhang JZ, et al., 2015, Wiring of Photosystem II to Hydrogenase for Photoelectrochemical Water Splitting, JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, Vol: 137, Pages: 8541-8549, ISSN: 0002-7863
Boussac A, Rutherford AW, Sugiura M, 2015, Electron transfer pathways from the S-2-states to the S-3-states either after a Ca2+/Sr2+ or a Cl-/I- exchange in Photosystem II from, BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS, Vol: 1847, Pages: 576-586, ISSN: 0005-2728
Cardona T, Murray JW, Rutherford AW, 2015, Origin and Evolution of Water Oxidation before the Last Common Ancestor of the Cyanobacteria, MOLECULAR BIOLOGY AND EVOLUTION, Vol: 32, Pages: 1310-1328, ISSN: 0737-4038
Rutherford AW, 2014, Redox tuning in biological electron transfer: sacrificing efficiency to survive life in O-2, 12th European Biological Inorganic Chemistry Conference (EuroBIC), Publisher: SPRINGER, Pages: S704-S704, ISSN: 0949-8257
Sugiura M, Azami C, Koyama K, et al., 2014, Modification of the pheophytin redox potential in Therrnosynechococcus elongatus Photosystem II with PsbA3 as D1, BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS, Vol: 1837, Pages: 139-148, ISSN: 0005-2728
Kato M, Cardona T, Rutherford AW, et al., 2013, Covalent Immobilization of Oriented Photosystem II on a Nanostructured Electrode for Solar Water Oxidation, JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, Vol: 135, Pages: 10610-10613, ISSN: 0002-7863
Saito K, Rutherford AW, Ishikita H, 2013, Mechanism of tyrosine D oxidation in Photosystem II, PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, Vol: 110, Pages: 7690-7695, ISSN: 0027-8424
Faunce T, Styring S, Wasielewski MR, et al., 2013, Artificial photosynthesis as a frontier technology for energy sustainability, ENERGY & ENVIRONMENTAL SCIENCE, Vol: 6, Pages: 1074-1076, ISSN: 1754-5692
Faunce TA, Lubitz W, Rutherford AWB, et al., 2013, Energy and environment policy case for a global project on artificial photosynthesis, ENERGY & ENVIRONMENTAL SCIENCE, Vol: 6, Pages: 695-698, ISSN: 1754-5692
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