title: Critical role of Chlamydomonas reinhardtii ferredoxin-5 in maintaining membrane structure and dark metabolism.
abstract: Photosynthetic microorganisms typically have multiple isoforms of the electron transfer protein ferredoxin, although we know little about their exact functions. Surprisingly, a Chlamydomonas reinhardtii mutant null for the ferredoxin-5 gene (FDX5) completely ceased growth in the dark, with both photosynthetic and respiratory functions severely compromised; growth in the light was unaffected. Thylakoid membranes in dark-maintained fdx5 mutant cells became severely disorganized concomitant with a marked decrease in the ratio of monogalactosyldiacylglycerol to digalactosyldiacylglycerol, major lipids in photosynthetic membranes, and the accumulation of triacylglycerol. Furthermore, FDX5 was shown to physically interact with the fatty acid desaturases CrΔ4FAD and CrFAD6, likely donating electrons for the desaturation of fatty acids that stabilize monogalactosyldiacylglycerol. Our results suggest that in photosynthetic organisms, specific redox reactions sustain dark metabolism, with little impact on daytime growth, likely reflecting the tailoring of electron carriers to unique intracellular metabolic circuits under these two very distinct redox conditions.
authors.affiliation: Department of Plant Biology, Carnegie Institution for Science, Stanford, CA 94305; wenqiangy@gmail.com.
authors.forename: Wenqiang
authors.identifier: 0000-0001-5600-4076
authors.initials: W
authors.lastname: Yang
authors.affiliation: Department of Plant Biology, Carnegie Institution for Science, Stanford, CA 94305; Department of Biology, Stanford University, Stanford, CA 94305;
authors.forename: Tyler M
authors.initials: TM
authors.lastname: Wittkopp
authors.affiliation: Department of Plant Biology, Carnegie Institution for Science, Stanford, CA 94305;
authors.forename: Xiaobo
authors.identifier: 0000-0003-3951-9646
authors.initials: X
authors.lastname: Li
authors.affiliation: Department of Plant Biology, Michigan State University, East Lansing, MI 48824;
authors.forename: Jaruswan
authors.initials: J
authors.lastname: Warakanont
authors.affiliation: National Renewable Energy Laboratory, Golden, CO 80401;
authors.forename: Alexandra
authors.initials: A
authors.lastname: Dubini
authors.affiliation: Department of Plant Biology, Carnegie Institution for Science, Stanford, CA 94305;
authors.forename: Claudia
authors.initials: C
authors.lastname: Catalanotti
authors.affiliation: Department of Plant Biology, Carnegie Institution for Science, Stanford, CA 94305; Department of Biology, Stanford University, Stanford, CA 94305;
authors.forename: Rick G
authors.initials: RG
authors.lastname: Kim
authors.affiliation: Department of Plant Biology, Carnegie Institution for Science, Stanford, CA 94305;
authors.forename: Eva C M
authors.initials: EC
authors.lastname: Nowack
authors.affiliation: Department of Plant Biology, Carnegie Institution for Science, Stanford, CA 94305;
authors.forename: Luke C M
authors.initials: LC
authors.lastname: Mackinder
authors.affiliation: Department of Plant Biology, Carnegie Institution for Science, Stanford, CA 94305;
authors.forename: Munevver
authors.initials: M
authors.lastname: Aksoy
authors.affiliation: Department of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095;
authors.forename: Mark Dudley
authors.initials: MD
authors.lastname: Page
authors.affiliation: Department of Chemistry and Geochemistry, Colorado School of Mines, Golden, CO 80401;
authors.forename: Sarah
authors.initials: S
authors.lastname: D'Adamo
authors.affiliation: Department of Plant Biology, Carnegie Institution for Science, Stanford, CA 94305;
authors.forename: Shai
authors.initials: S
authors.lastname: Saroussi
authors.affiliation: Department of Plant Biology, Carnegie Institution for Science, Stanford, CA 94305;
authors.forename: Mark
authors.initials: M
authors.lastname: Heinnickel
authors.affiliation: Department of Plant Biology, Carnegie Institution for Science, Stanford, CA 94305; Commissariat à l'Énergie Atomique, Centre National de la Recherche Scientifique, Aix-Marseille Université, Cadarache, Saint-Paul-lez-Durance F-13108, France;
authors.forename: Xenie
authors.initials: X
authors.lastname: Johnson
authors.affiliation: Commissariat à l'Énergie Atomique, Centre National de la Recherche Scientifique, Aix-Marseille Université, Cadarache, Saint-Paul-lez-Durance F-13108, France;
authors.forename: Pierre
authors.initials: P
authors.lastname: Richaud
authors.affiliation: Department of Plant Biology, Carnegie Institution for Science, Stanford, CA 94305; Commissariat à l'Énergie Atomique, Centre National de la Recherche Scientifique, Aix-Marseille Université, Cadarache, Saint-Paul-lez-Durance F-13108, France;
authors.forename: Jean
authors.initials: J
authors.lastname: Alric
authors.affiliation: National Renewable Energy Laboratory, Golden, CO 80401;
authors.forename: Marko
authors.initials: M
authors.lastname: Boehm
authors.affiliation: Department of Plant Biology, Carnegie Institution for Science, Stanford, CA 94305;
authors.forename: Martin C
authors.initials: MC
authors.lastname: Jonikas
authors.affiliation: Michigan State University-Department of Energy Plant Research Laboratory, Michigan State University, East Lansing, MI 48824;
authors.forename: Christoph
authors.initials: C
authors.lastname: Benning
authors.affiliation: Department of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095; Institute of Genomics and Proteomics, University of California, Los Angeles, CA 90095.
authors.forename: Sabeeha S
authors.initials: SS
authors.lastname: Merchant
authors.affiliation: Department of Chemistry and Geochemistry, Colorado School of Mines, Golden, CO 80401;
authors.forename: Matthew C
authors.initials: MC
authors.lastname: Posewitz
authors.affiliation: Department of Plant Biology, Carnegie Institution for Science, Stanford, CA 94305;
authors.forename: Arthur R
authors.initials: AR
authors.lastname: Grossman
mesh_terms: D016825:Chlamydomonas reinhardtii / Q000201:enzymology* / Q000235:genetics; D044943:Fatty Acid Desaturases / Q000235:genetics / Q000378:metabolism*; D005288:Ferredoxins / Q000235:genetics / Q000378:metabolism*; D038983:Galactolipids / Q000235:genetics / Q000378:metabolism*; D010084:Oxidation-Reduction; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D020524:Thylakoids / Q000235:genetics / Q000378:metabolism*
chemical_list: C081714:2Fe-2S ferredoxin; D005288:Ferredoxins; D038983:Galactolipids; D010940:Plant Proteins; C007388:digalactosyldiacylglycerol; D044943:Fatty Acid Desaturases
keywords: dark growth; ferredoxin; redox regulation; thylakoid lipids; triacylglycerol