Role of bicarbonate at the acceptor side of Photosystem II

Rensen, J.J.S. van

doi:10.1007/1-4020-3324-9_29

Cited by 19 publications

(26 citation statements)

References 45 publications

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“…(2) Leaf photosynthesis can maintain a basal level of activity during partial or full stomatal closure. Low CO 2 levels in combination with high light intensities could increase the photooxidative risk and lead to instability of the PSII (Murata et al, 2007;van Rensen, 2002). Thus, alarm photosynthesis could act as a quenching valve for the energy excess accumulated in the electron transport chain, when the light reactions are not in pace with photosynthetic CO 2 assimilation from the atmosphere.…”

Section: Resultsmentioning

confidence: 99%

Alarm Photosynthesis: Calcium Oxalate Crystals as an Internal CO₂ Source in Plants

et al. 2016

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Calcium oxalate crystals are widespread among animals and plants. In land plants, crystals often reach high amounts, up to 80% of dry biomass. They are formed within specific cells, and their accumulation constitutes a normal activity rather than a pathological symptom, as occurs in animals. Despite their ubiquity, our knowledge on the formation and the possible role(s) of these crystals remains limited. We show that the mesophyll crystals of pigweed (Amaranthus hybridus) exhibit diurnal volume changes with a gradual decrease during daytime and a total recovery during the night. Moreover, stable carbon isotope composition indicated that crystals are of nonatmospheric origin. Stomatal closure (under drought conditions or exogenous application of abscisic acid) was accompanied by crystal decomposition and by increased activity of oxalate oxidase that converts oxalate into CO 2 . Similar results were also observed under drought stress in Dianthus chinensis, Pelargonium peltatum, and Portulacaria afra. Moreover, in A. hybridus, despite closed stomata, the leaf metabolic profiles combined with chlorophyll fluorescence measurements indicated active photosynthetic metabolism. In combination, calcium oxalate crystals in leaves can act as a biochemical reservoir that collects nonatmospheric carbon, mainly during the night. During the day, crystal degradation provides subsidiary carbon for photosynthetic assimilation, especially under drought conditions. This new photosynthetic path, with the suggested name "alarm photosynthesis," seems to provide a number of adaptive advantages, such as water economy, limitation of carbon losses to the atmosphere, and a lower risk of photoinhibition, roles that justify its vast presence in plants.

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Section: Resultsmentioning

confidence: 99%

Alarm Photosynthesis: Calcium Oxalate Crystals as an Internal CO₂ Source in Plants

et al. 2016

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“…Bicarbonate is an important anion that modulates electron transport in photosystem II between Q A and Q B (9) and is involved in donor side reactions of PSII (11,29,42). It is also, of course, the hydrated form of CO 2 used by cells for the Calvin-Benson-Bassham cycle, and in Arthrospira HCO 3 Ϫ is the dominant form of inorganic carbon that can enter the cell (8,11).…”

Section: Discussionmentioning

confidence: 99%

Optimization of Metabolic Capacity and Flux through Environmental Cues To Maximize Hydrogen Production by the Cyanobacterium “ Arthrospira ( Spirulina ) maxima ”

Ananyev

Carrieri

Dismukes

2008

Appl Environ Microbiol

116

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Environmental and nutritional conditions that optimize the yield of hydrogen (H 2 ) from water using a two-step photosynthesis/fermentation (P/F) process are reported for the hypercarbonate-requiring cyanobacterium "Arthrospira maxima." Our observations lead to four main conclusions broadly applicable to fermentative H 2 production by bacteria: (i) anaerobic H 2 production in the dark from whole cells catalyzed by a bidirectional [NiFe] hydrogenase is demonstrated to occur in two temporal phases involving two distinct metabolic processes that are linked to prior light-dependent production of NADPH (photosynthetic) and dark/anaerobic production of NADH (fermentative), respectively; (ii) H 2 evolution from these reductants represents a major pathway for energy production (ATP) during fermentation by regenerating NAD ؉ essential for glycolysis of glycogen and catabolism of other substrates; (iii) nitrate removal during fermentative H 2 evolution is shown to produce an immediate and large stimulation of H 2 , as nitrate is a competing substrate for consumption of NAD(P)H, which is distinct from its slower effect of stimulating glycogen accumulation; (iv) environmental and nutritional conditions that increase anaerobic ATP production, prior glycogen accumulation (in the light), and the intracellular reduction potential (NADH/NAD ؉ ratio) are shown to be the key variables for elevating H 2 evolution. Optimization of these conditions and culture age increases the H 2 yield from a single P/F cycle using concentrated cells to 36 ml of H 2 /g (dry weight) and a maximum 18% H 2 in the headspace. H 2 yield was found to be limited by the hydrogenase-mediated H 2 uptake reaction.

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“…Bicarbonate has been clearly shown to bind at the non-heme iron of the acceptor side of PSII (Ferreira et al, 2004) and to be of functional relevance for electron transfer at this position (for a recent review, see van Rensen, 2002). In addition, there is evidence that bicarbonate also affects oxygen evolution directly.…”

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confidence: 99%

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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Role of bicarbonate at the acceptor side of Photosystem II

Cited by 19 publications

References 45 publications

Alarm Photosynthesis: Calcium Oxalate Crystals as an Internal CO₂ Source in Plants

Alarm Photosynthesis: Calcium Oxalate Crystals as an Internal CO₂ Source in Plants

Optimization of Metabolic Capacity and Flux through Environmental Cues To Maximize Hydrogen Production by the Cyanobacterium “ Arthrospira ( Spirulina ) maxima ”

Evidence That Bicarbonate Is Not the Substrate in Photosynthetic Oxygen Evolution

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Role of bicarbonate at the acceptor side of Photosystem II

Cited by 19 publications

References 45 publications

Alarm Photosynthesis: Calcium Oxalate Crystals as an Internal CO2 Source in Plants

Alarm Photosynthesis: Calcium Oxalate Crystals as an Internal CO2 Source in Plants

Optimization of Metabolic Capacity and Flux through Environmental Cues To Maximize Hydrogen Production by the Cyanobacterium “ Arthrospira ( Spirulina ) maxima ”

Evidence That Bicarbonate Is Not the Substrate in Photosynthetic Oxygen Evolution

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Alarm Photosynthesis: Calcium Oxalate Crystals as an Internal CO₂ Source in Plants

Alarm Photosynthesis: Calcium Oxalate Crystals as an Internal CO₂ Source in Plants