title: Flavodiiron proteins act as safety valve for electrons in Physcomitrella patens.
abstract: Photosynthetic organisms support cell metabolism by harvesting sunlight to fuel the photosynthetic electron transport. The flow of excitation energy and electrons in the photosynthetic apparatus needs to be continuously modulated to respond to dynamics of environmental conditions, and Flavodiiron (FLV) proteins are seminal components of this regulatory machinery in cyanobacteria. FLVs were lost during evolution by flowering plants, but are still present in nonvascular plants such as Physcomitrella patens We generated P. patens mutants depleted in FLV proteins, showing their function as an electron sink downstream of photosystem I for the first seconds after a change in light intensity. flv knock-out plants showed impaired growth and photosystem I photoinhibition when exposed to fluctuating light, demonstrating FLV's biological role as a safety valve from excess electrons on illumination changes. The lack of FLVs was partially compensated for by an increased cyclic electron transport, suggesting that in flowering plants, the FLV's role was taken by other alternative electron routes.
authors: Department of Biology, University of Padova, 35121 Padova, Italy.
authors: Caterina
authors: C
authors: Gerotto
authors: Department of Biology, University of Padova, 35121 Padova, Italy.
authors: Alessandro
authors: 0000-0003-4818-7778
authors: A
authors: Alboresi
authors: Department of Biology, University of Padova, 35121 Padova, Italy.
authors: Andrea
authors: A
authors: Meneghesso
authors: Department of Biochemistry, Molecular Plant Biology, University of Turku, FI-20014 Turku, Finland.
authors: Martina
authors: M
authors: Jokel
authors: Department of Biochemistry, Molecular Plant Biology, University of Turku, FI-20014 Turku, Finland.
authors: Marjaana
authors: M
authors: Suorsa
authors: Department of Biochemistry, Molecular Plant Biology, University of Turku, FI-20014 Turku, Finland.
authors: Eva-Mari
authors: EM
authors: Aro
authors: Department of Biology, University of Padova, 35121 Padova, Italy; tomas.morosinotto@unipd.it.
authors: Tomas
authors: 0000-0002-0803-7591
authors: T
authors: Morosinotto
mesh_terms: D019068:Bryopsida / Q000235:genetics* / Q000254:growth & development; D004579:Electron Transport / Q000235:genetics; D019143:Evolution, Molecular; D050505:Mutant Proteins / Q000235:genetics / Q000378:metabolism; D010100:Oxygen / Q000378:metabolism; D010788:Photosynthesis / Q000235:genetics*; D010940:Plant Proteins / Q000235:genetics*; D013472:Sunlight
chemical_list: D050505:Mutant Proteins; D010940:Plant Proteins; D010100:Oxygen
keywords: electron transport; mosses; photoprotection; photosynthesis; plant evolution