title: Arabidopsis tic62 trol mutant lacking thylakoid-bound ferredoxin-NADP+ oxidoreductase shows distinct metabolic phenotype.
abstract: Ferredoxin-NADP+ oxidoreductase (FNR), functioning in the last step of the photosynthetic electron transfer chain, exists both as a soluble protein in the chloroplast stroma and tightly attached to chloroplast membranes. Surface plasmon resonance assays showed that the two FNR isoforms, LFNR1 and LFNR2, are bound to the thylakoid membrane via the C-terminal domains of Tic62 and TROL proteins in a pH-dependent manner. The tic62 trol double mutants contained a reduced level of FNR, exclusively found in the soluble stroma. Although the mutant plants showed no visual phenotype or defects in the function of photosystems under any conditions studied, a low ratio of NADPH/NADP+ was detected. Since the CO₂ fixation capacity did not differ between the tic62 trol plants and wild-type, it seems that the plants are able to funnel reducing power to most crucial reactions to ensure survival and fitness of the plants. However, the activity of malate dehydrogenase was down-regulated in the mutant plants. Apparently, the plastid metabolism is able to cope with substantial changes in directing the electrons from the light reactions to stromal metabolism and thus only few differences are visible in steady-state metabolite pool sizes of the tic62 trol plants.
authors.affiliation: Molecular Plant Biology, Department of Biochemistry, University of Turku, FI-20014 Turku, Finland.
authors.forename: Minna
authors.initials: M
authors.lastname: Lintala
authors.forename: Natalie
authors.initials: N
authors.lastname: Schuck
authors.forename: Ina
authors.initials: I
authors.lastname: Thormählen
authors.forename: Andreas
authors.initials: A
authors.lastname: Jungfer
authors.forename: Katrin L
authors.initials: KL
authors.lastname: Weber
authors.forename: Andreas P M
authors.initials: AP
authors.lastname: Weber
authors.forename: Peter
authors.initials: P
authors.lastname: Geigenberger
authors.forename: Jürgen
authors.initials: J
authors.lastname: Soll
authors.forename: Bettina
authors.initials: B
authors.lastname: Bölter
authors.forename: Paula
authors.initials: P
authors.lastname: Mulo
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000166:cytology / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D002736:Chloroplasts / Q000378:metabolism; D005287:Ferredoxin-NADP Reductase / Q000172:deficiency*; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D026901:Membrane Transport Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D009249:NADP / Q000378:metabolism; D010084:Oxidation-Reduction; D010641:Phenotype; D013213:Starch / Q000096:biosynthesis; D020524:Thylakoids / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; C547211:TROL protein, Arabidopsis; C520728:Tic62 protein, Arabidopsis; D009249:NADP; D013213:Starch; D005287:Ferredoxin-NADP Reductase
keywords: TROL.; Tic62; carbon assimilation; chloroplast; ferredoxin–NADP+ oxidoreductase; photosynthesis; stromal metabolism