ORCID Profile
0000-0003-0371-938X
Current Organisation
Institut de recherche pour le développement France-Sud
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Publisher: Elsevier BV
Date: 07-2011
Publisher: Cold Spring Harbor Laboratory
Date: 23-12-2019
DOI: 10.1101/2019.12.23.886929
Abstract: In oxygenic photosynthetic organisms excluding angiosperms, flavodiiron proteins (FDPs) catalyze light-dependent reduction of O 2 to H 2 O. This alleviates electron pressure on the photosynthetic apparatus and protects it from photodamage. In Synechocystis sp. PCC 6803, four FDP isoforms function as hetero-oligomers of Flv1 and Flv3 and/or Flv2 and Flv4. An alternative electron transport pathway mediated by the NAD(P)H dehydrogenase-like complex (NDH-1) also contributes to redox hemostasis and the photoprotection of photosynthesis. Four NDH-1 types haven been characterized in cyanobacteria: NDH-1 1 and NDH-1 2 , which function in respiration and NDH-1 3 and NDH-1 4 , which function in CO 2 uptake. All four types are involved in cyclic electron transport. Along with single FDP mutants (Δ flv1 and Δ flv3 ) and the double NDH-1 mutants (Δ d1d2 , which is deficient in NDH-1 1,2 and Δ d3d4 , which is deficient in NDH-1 3,4 ), we studied triple mutants lacking either one of Flv1 or Flv3, and NDH-1 1,2 or NDH-1 3,4 . We show that the presence of either Flv1/3 or NDH-1 1,2 , but not NDH-1 3,4 , is indispensable for survival during changes in growth conditions from high CO 2 /moderate light to low CO 2 / high light. Our results suggest functional redundancy and crosstalk between FDPs and NDH-1 1,2 under the studied conditions, and demonstrate that the functions of FDPs and NDH-1 1,2 are dynamically coordinated for the efficient oxidation of PSI and for photoprotection under variable CO 2 and light availability. Flavodiiron proteins and NDH-1 complex ensure survival of cyanobacterial cells by cooperatively safeguarding the photosynthetic apparatus against excessive reduction
Publisher: Proceedings of the National Academy of Sciences
Date: 04-02-2013
Abstract: Cyanobacterial flavodiiron proteins (FDPs A-type flavoprotein, Flv) comprise, besides the β-lactamase–like and flavodoxin domains typical for all FDPs, an extra NAD(P)H:flavin oxidoreductase module and thus differ from FDPs in other Bacteria and Archaea. Synechocystis sp. PCC 6803 has four genes encoding the FDPs. Flv1 and Flv3 function as an NAD(P)H:oxygen oxidoreductase, donating electrons directly to O 2 without production of reactive oxygen species. Here we show that the Flv1 and Flv3 proteins are crucial for cyanobacteria under fluctuating light, a typical light condition in aquatic environments. Under constant-light conditions, regardless of light intensity, the Flv1 and Flv3 proteins are dispensable. In contrast, under fluctuating light conditions, the growth and photosynthesis of the Δ flv1(A) and/or Δ flv3(A) mutants of Synechocystis sp. PCC 6803 and Anabaena sp. PCC 7120 become arrested, resulting in cell death in the most severe cases. This reaction is mainly caused by malfunction of photosystem I and oxidative damage induced by reactive oxygen species generated during abrupt short-term increases in light intensity. Unlike higher plants that lack the FDPs and use the Proton Gradient Regulation 5 to safeguard photosystem I, the cyanobacterial homolog of Proton Gradient Regulation 5 is shown not to be crucial for growth under fluctuating light. Instead, the unique Flv1/Flv3 heterodimer maintains the redox balance of the electron transfer chain in cyanobacteria and provides protection for photosystem I under fluctuating growth light. Evolution of unique cyanobacterial FDPs is discussed as a prerequisite for the development of oxygenic photosynthesis.
Publisher: Wiley
Date: 16-06-2020
DOI: 10.1111/TPJ.14812
Abstract: In oxygenic photosynthetic organisms, excluding angiosperms, flavodiiron proteins (FDPs) catalyze light‐dependent reduction of O 2 to H 2 O. This alleviates electron pressure on the photosynthetic apparatus and protects it from photodamage. In Synechocystis sp. PCC 6803, four FDP isoforms function as hetero‐oligomers of Flv1 and Flv3 and/or Flv2 and Flv4. An alternative electron transport pathway mediated by the NAD(P)H dehydrogenase‐like complex (NDH‐1) also contributes to redox hemostasis and the photoprotection of photosynthesis. Four NDH‐1 types have been characterized in cyanobacteria: NDH‐1 1 and NDH‐1 2 , which function in respiration and NDH‐1 3 and NDH‐1 4 , which function in CO 2 uptake. All four types are involved in cyclic electron transport. Along with single FDP mutants (∆ flv1 and Δ flv3 ) and the double NDH‐1 mutants (∆ d1d2 , which is deficient in NDH‐1 1,2 and ∆ d3d4 , which is deficient in NDH‐1 3,4 ), we studied triple mutants lacking one of Flv1 or Flv3, and NDH‐1 1,2 or NDH‐1 3,4 . We show that the presence of either Flv1/3 or NDH‐1 1,2 , but not NDH‐1 3,4 , is indispensable for survival during changes in growth conditions from high CO 2 /moderate light to low CO 2 /high light. Our results show functional redundancy between FDPs and NDH‐1 1,2 under the studied conditions. We suggest that ferredoxin probably functions as a primary electron donor to both Flv1/3 and NDH‐1 1,2 , allowing their functions to be dynamically coordinated for efficient oxidation of photosystem I and for photoprotection under variable CO 2 and light availability.
Publisher: Proceedings of the National Academy of Sciences
Date: 07-07-2014
Abstract: Cyanobacterial flavodiiron proteins (FDPs) comprise a protein family with unique modular structure and photoprotective functions in an oxygenic environment. It is conceivable that FDPs have made the development of oxygenic photosynthesis possible in cyanobacteria. Here, we report the ability of specific FDPs to reduce O 2 directly to water in heterocyst-forming filamentous cyanobacteria, not only to support the photosynthetic machinery, but also to prevent oxidative damage of the N 2 -fixing enzyme nitrogenase. Whilst in the ancient environment, N 2 fixation was secured from O 2 inhibition, the later increase of atmospheric O 2 may have initiated an important role for FDP-mediated protection of nitrogenase in maintaining the N 2 -fixing activity of cyanobacteria.
Location: France
Location: France
Location: No location found
No related grants have been discovered for Laurent Cournac.