Horizon 1 1 17 ACL : Articles dans des revues avec comité de lecture répertoriées par l'AERES Plant Journal 1460-1476 Flavodiiron proteins Flv NDH-1 photosynthesis Synechocystis sp PCC 6803 cyanobacteria Mehler-like reaction alternative electron transfer photoprotection 2020 fdi:010078179 ENG Plant Journal 0960-7412 ISI:000540294000001 4 10.1111/tpj.14812 https://www.documentation.ird.fr/hor/fdi:010078179 https://horizon.documentation.ird.fr/exl-doc/pleins_textes/divers20-07/010078179.pdf 103 Horizon (IRD) In oxygenic photosynthetic organisms, excluding angiosperms, flavodiiron proteins (FDPs) catalyze light-dependent reduction of O(2)to H2O. This alleviates electron pressure on the photosynthetic apparatus and protects it from photodamage. InSynechocystissp. 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 ( increment flv1and Delta flv3) and the double NDH-1 mutants ( increment d1d2, which is deficient in NDH-1(1,2)and increment 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 CO2/moderate light to low CO2/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. 076 ; 034 ; 020 UR210