title: Tetratricopeptide repeat protein protects photosystem I from oxidative disruption during assembly.
abstract: A Chlamydomonas reinhardtii mutant lacking CGL71, a thylakoid membrane protein previously shown to be involved in photosystem I (PSI) accumulation, exhibited photosensitivity and highly reduced abundance of PSI under photoheterotrophic conditions. Remarkably, the PSI content of this mutant declined to nearly undetectable levels under dark, oxic conditions, demonstrating that reduced PSI accumulation in the mutant is not strictly the result of photodamage. Furthermore, PSI returns to nearly wild-type levels when the O2 concentration in the medium is lowered. Overall, our results suggest that the accumulation of PSI in the mutant correlates with the redox state of the stroma rather than photodamage and that CGL71 functions under atmospheric O2 conditions to allow stable assembly of PSI. These findings may reflect the history of the Earth's atmosphere as it transitioned from anoxic to highly oxic (1-2 billion years ago), a change that required organisms to evolve mechanisms to assist in the assembly and stability of proteins or complexes with O2-sensitive cofactors.
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; Department of Biology, Stanford University, Stanford, CA 94305; rgkim9@gmail.com.
authors.forename: Rick G
authors.initials: RG
authors.lastname: Kim
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: Wenqiang
authors.initials: W
authors.lastname: Yang
authors.affiliation: Department of Chemistry, Pennsylvania State University, University Park, PA 16802;
authors.forename: Karim A
authors.initials: KA
authors.lastname: Walters
authors.affiliation: Department of Plant Biology, Carnegie Institution for Science, Stanford, CA 94305; Department of Plant Sciences, University of Wyoming, Laramie, WY 82071.
authors.forename: Stephen K
authors.initials: SK
authors.lastname: Herbert
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: D020418:Algal Proteins / Q000235:genetics / Q000378:metabolism*; D016825:Chlamydomonas reinhardtii / Q000235:genetics / Q000378:metabolism*; D060365:Chloroplast Proteins / Q000235:genetics / Q000378:metabolism*; D004579:Electron Transport / Q000235:genetics / Q000528:radiation effects; D015151:Immunoblotting; D007700:Kinetics; D008027:Light; D009154:Mutation; D010084:Oxidation-Reduction; D010100:Oxygen / Q000378:metabolism; D010788:Photosynthesis / Q000235:genetics / Q000528:radiation effects; D045331:Photosystem I Protein Complex / Q000235:genetics / Q000378:metabolism*; D060431:Thylakoid Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D020524:Thylakoids / Q000378:metabolism
chemical_list: D020418:Algal Proteins; D060365:Chloroplast Proteins; D045331:Photosystem I Protein Complex; D060431:Thylakoid Membrane Proteins; D010100:Oxygen
keywords: GreenCut; oxidative disruption; photosynthesis; photosystem I biogenesis