title: TROL-FNR interaction reveals alternative pathways of electron partitioning in photosynthesis.
abstract: In photosynthesis, final electron transfer from ferredoxin to NADP(+) is accomplished by the flavo enzyme ferredoxin:NADP(+) oxidoreductase (FNR). FNR is recruited to thylakoid membranes via integral membrane thylakoid rhodanase-like protein TROL. We address the fate of electrons downstream of photosystem I when TROL is absent. We have employed electron paramagnetic resonance (EPR) spectroscopy to study free radical formation and electron partitioning in TROL-depleted chloroplasts. DMPO was used to detect superoxide anion (O2(.-)) formation, while the generation of other free radicals was monitored by Tiron. Chloroplasts from trol plants pre-acclimated to different light conditions consistently exhibited diminished O2(.-) accumulation. Generation of other radical forms was elevated in trol chloroplasts in all tested conditions, except for the plants pre-acclimated to high-light. Remarkably, dark- and growth light-acclimated trol chloroplasts were resilient to O2(.-) generation induced by methyl-viologen. We propose that the dynamic binding and release of FNR from TROL can control the flow of photosynthetic electrons prior to activation of the pseudo-cyclic electron transfer pathway.
authors.affiliation: Division of Molecular Biology, Ruđer Bošković Institute, 10000 Zagreb, Croatia.
authors.forename: Lea
authors.initials: L
authors.lastname: Vojta
authors.affiliation: Division of Physical Chemistry, Ruđer Bošković Institute, 10000 Zagreb, Croatia.
authors.forename: Dejana
authors.initials: D
authors.lastname: Carić
authors.affiliation: Department of Biology, JJ Strossmayer University of Osijek, 31000 Osijek, Croatia.
authors.forename: Vera
authors.initials: V
authors.lastname: Cesar
authors.affiliation: Department of Biology, JJ Strossmayer University of Osijek, 31000 Osijek, Croatia.
authors.forename: Jasenka
authors.initials: J
authors.lastname: Antunović Dunić
authors.affiliation: Agricultural Institute Osijek, 31000 Osijek, Croatia.
authors.forename: Hrvoje
authors.initials: H
authors.lastname: Lepeduš
authors.affiliation: Division of Physical Chemistry, Ruđer Bošković Institute, 10000 Zagreb, Croatia.
authors.forename: Marina
authors.initials: M
authors.lastname: Kveder
authors.affiliation: Division of Molecular Biology, Ruđer Bošković Institute, 10000 Zagreb, Croatia.
authors.forename: Hrvoje
authors.initials: H
authors.lastname: Fulgosi
mesh_terms: D017360:Arabidopsis / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000378:metabolism*; D002736:Chloroplasts / Q000378:metabolism; D004579:Electron Transport; D005287:Ferredoxin-NADP Reductase / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism*; D053858:Metabolic Networks and Pathways; D010100:Oxygen / Q000378:metabolism; D017440:Photoperiod; D010788:Photosynthesis; D017382:Reactive Oxygen Species / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D008565:Membrane Proteins; D017382:Reactive Oxygen Species; C547211:TROL protein, Arabidopsis; D005287:Ferredoxin-NADP Reductase; D010100:Oxygen