Isotopic composition of photosynthetic O2 flash yields in the presence of H218O and HC18O−3

Radmer, Richard; Ollinger, Otto

doi:10.1016/0014-5793(80)80022-6

Cited by 72 publications

(43 citation statements)

References 9 publications

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“…Stemler and Govindjee were the first to observe an effect of dissolved CO 2 on electron transport (17), and they suggested a possible site for bicarbonate binding on the donor side of PSII involved in stimulating water oxidation. This view was further advocated by Stemler (18) but later refuted by Radmer and Ollinger based on isotopic studies (19). These contradictions, together with the discovery of a low affinity binding site for bicarbonate on the PSII acceptor side, at the non-heme iron site involved in stimulating secondary electron transfer steps out of PSII, shifted attention away from a possible site for bicarbonate functioning on the donor side.…”

Section: Was There a Transitional Electron Donor Before Water?mentioning

confidence: 99%

The origin of atmospheric oxygen on Earth: The innovation of oxygenic photosynthesis

Dismukes

Klimov

Baranov

et al. 2001

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

328

240

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The evolution of O2-producing cyanobacteria that use water as terminal reductant transformed Earth's atmosphere to one suitable for the evolution of aerobic metabolism and complex life. The innovation of water oxidation freed photosynthesis to invade new environments and visibly changed the face of the Earth. We offer a new hypothesis for how this process evolved, which identifies two critical roles for carbon dioxide in the Archean period. First, we present a thermodynamic analysis showing that bicarbonate (formed by dissolution of CO 2) is a more efficient alternative substrate than water for O 2 production by oxygenic phototrophs. This analysis clarifies the origin of the long debated ''bicarbonate effect'' on photosynthetic O 2 production. We propose that bicarbonate was the thermodynamically preferred reductant before water in the evolution of oxygenic photosynthesis. Second, we have examined the speciation of manganese(II) and bicarbonate in water, and find that they form Mnbicarbonate clusters as the major species under conditions that model the chemistry of the Archean sea. These clusters have been found to be highly efficient precursors for the assembly of the tetramanganese-oxide core of the water-oxidizing enzyme during biogenesis. We show that these clusters can be oxidized at electrochemical potentials that are accessible to anoxygenic phototrophs and thus the most likely building blocks for assembly of the first O 2 evolving photoreaction center, most likely originating from green nonsulfur bacteria before the evolution of cyanobacteria.bicarbonate ͉ carbon dioxide ͉ cyanobacteria ͉ evolution ͉ manganese O xygen (O 2 ) production by photosynthesis is by far the dominant global process that replenishes atmospheric and oceanic oxygen essential to sustain all aerobic life. Geochemical records of terrestrial oxides indicate that O 2 evolution must have taken place in the precursors to cyanobacteria before ca. 2.8 billion years ago and led to the accumulation of O 2 in the atmosphere (1, 2). The creation of a photosynthetic apparatus capable of splitting water into O 2 , protons, and electrons was the pivotal innovation in the evolution of life on Earth. For the first time photosynthesis had an unlimited source of electrons and protons by using water as reductant. By freeing photosynthesis from the availability of reduced chemical substances, the global production of organic carbon could be enormously increased and opened new environments for photosynthesis to occur. This event literally changed the face of the Earth. The accumulation of O 2 in the atmosphere led to the biological innovation of aerobic respiration, which harnesses a more powerful metabolic energy source. Because aerobic metabolism generates 18 times more energy (ATP) per metabolic input (hexose sugar) than does anaerobic metabolism, the engine of life became supercharged. This sequence of evolutionary steps enabled the emergence of complex, multicellular, energy-efficient, eukaryotic organisms.Comparisons of cyanobacteria, green algae, ...

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Section: Was There a Transitional Electron Donor Before Water?mentioning

confidence: 99%

The origin of atmospheric oxygen on Earth: The innovation of oxygenic photosynthesis

Dismukes

Klimov

Baranov

et al. 2001

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

328

240

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“…O (Radmer and Ollinger, 1980;Bader et al, 1987;Messinger et al, 1995;Hillier et al, 1998;Hillier and Wydrzynski, 2000). Strictly speaking, however, these data are still compatible with a catalytic role of bicarbonate if the equilibrium between water, CO 2 , and bicarbonate is rapidly installed, as mediated, for example, by a carbonic anhydrase (CA; Silverman and Tu, 1975;Tu and Silverman, 1975).…”

mentioning

confidence: 91%

Evidence That Bicarbonate Is Not the Substrate in Photosynthetic Oxygen Evolution

et al. 2005

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(J.C., W.J.); and Max-PlanckInstitut fü r Bioanorganische Chemie, 45470 Muelheim an der Ruhr, Germany (K.B., J.M.)It is widely accepted that the oxygen produced by photosystem II of cyanobacteria, algae, and plants is derived from water. Earlier proposals that bicarbonate may serve as substrate or catalytic intermediate are almost forgotten, though not rigorously disproved. These latter proposals imply that CO 2 is an intermediate product of oxygen production in addition to O 2 . In this work, we investigated this possible role of exchangeable HCO 3 2 in oxygen evolution in two independent ways. (1) We studied a possible product inhibition of the electron transfer into the catalytic Mn 4 Ca complex during the oxygen-evolving reaction by greatly increasing the pressure of CO 2 . This was monitored by absorption transients in the near UV. We found that a 3,000-fold increase of the CO 2 pressure over ambient conditions did not affect the UV transient, whereas the S 3 / S 4 / S 0 transition was half-inhibited by raising the O 2 pressure only 10-fold over ambient, as previously established. (2) The flash-induced O 2 and CO 2 production by photosystem II was followed simultaneously with membrane inlet mass spectrometry under approximately 15% H 2 18 O enrichment. Light flashes that revealed the known oscillatory O 2 release failed to produce any oscillatory CO 2 signal. Both types of results exclude that exchangeable bicarbonate is the substrate for (and CO 2 an intermediate product of) oxygen evolution by photosynthesis. The possibility that a tightly bound carbonate or bicarbonate is a cofactor of photosynthetic water oxidation has remained.

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“…This signal (split + To whom correspondence should be addressed It is known that absence of CO2 (in the presence of formate) leads to a blockage of electron flow between QA and the plastoquinone pool [lo], whereas steady-state electron flow from Hz0 to QA does not appear to be impaired [11,12]. However, the QA oxidation by the water splitting system is slowed down in the absence of HCOp [13,14], whereas also the oxidation of QA by the oneelectron acceptor C400 [15] was interpreted to be blocked in the absence of HCO; [16], although this interpretation was questioned recently [ 171. In addition, COZ, and probably also the redox state of QA, can modulate herbicide affinity [12,18,19].…”

Section: Introductionmentioning

confidence: 99%

EPR measurements on the effects of bicarbonate and triazine resistance on the acceptor side of Photosystem II

Vermaas

Rutherford²

1984

FEBS Letters

124

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CO* depletion leads to an approximately IO-fold increase in the light-induced EPR signal at g = 1.82, attributed to the Qi. Fe*+ complex, in Photosystem II-enriched thylakoid membrane fragments. Upon reconstitution with HCO;the signal decreases to the size in control samples. The split pheophytin-signal is broader in control or reconstituted than in CO,-depleted samples. It is concluded that HCO; strongly influences the localization and conformation of the Q;. Fez+ complex. The QA * Fe*+ and split pheophytin-EPR signals from triazine-resistant Brassica napus were virtually identical to those from triazine-susceptible samples, indicating that the change in the 32-kDa azidoatrazine-binding protein does not lead to a conformational change of the Qi. Fe*+ complex. Semiquinone-iron complexPhotosystem II Bicarbonate effect Triazine resistance Photosynthesis Herbicide

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Isotopic composition of photosynthetic O₂ flash yields in the presence of H₂¹⁸O and HC¹⁸O⁻₃

Cited by 72 publications

References 9 publications

The origin of atmospheric oxygen on Earth: The innovation of oxygenic photosynthesis

The origin of atmospheric oxygen on Earth: The innovation of oxygenic photosynthesis

Evidence That Bicarbonate Is Not the Substrate in Photosynthetic Oxygen Evolution

EPR measurements on the effects of bicarbonate and triazine resistance on the acceptor side of Photosystem II

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