title: Genetically Programmed Changes in Photosynthetic Cofactor Metabolism in Copper-deficient Chlamydomonas.
abstract: Genetic and genomic studies indicate that copper deficiency triggers changes in the expression of genes encoding key enzymes in various chloroplast-localized lipid/pigment biosynthetic pathways. Among these are CGL78 involved in chlorophyll biosynthesis and HPPD1, encoding 4-hydroxyphenylpyruvate dioxygenase catalyzing the committed step of plastoquinone and tocopherol biosyntheses. Copper deficiency in wild-type cells does not change the chlorophyll content, but a survey of chlorophyll protein accumulation in this situation revealed increased accumulation of LHCSR3, which is blocked at the level of mRNA accumulation when either CGL78 expression is reduced or in the crd1 mutant, which has a copper-nutrition conditional defect at the same step in chlorophyll biosynthesis. Again, like copper-deficient crd1 strains, cgl78 knock-down lines also have reduced chlorophyll content concomitant with loss of PSI-LHCI super-complexes and reduced abundance of a chlorophyll binding subunit of PSI, PSAK, which connects LHCI to PSI. For HPPD1, increased mRNA results in increased abundance of the corresponding protein in copper-deficient cells concomitant with CRR1-dependent increased accumulation of γ-tocopherols, but not plastoquinone-9 nor total tocopherols. In crr1 mutants, where increased HPPD1 expression is blocked, plastochromanol-8, derived from plastoquinone-9 and purported to also have an antioxidant function, is found instead. Although not previously found in algae, this metabolite may occur only in stress conditions.
authors.affiliation: From the Institute for Genomics and Proteomics, University of California, Los Angeles, California 90095, the Department of Chemistry and Biochemistry, UCLA, Los Angeles, California 90095.
authors.forename: Daniela
authors.initials: D
authors.lastname: Strenkert
authors.affiliation: the Department of Chemistry and Biochemistry, UCLA, Los Angeles, California 90095.
authors.forename: Clariss Ann
authors.initials: CA
authors.lastname: Limso
authors.affiliation: the Institut Jean-Pierre Bourgin, UMR1318 INRA-AgroParisTech, 78026 Versailles Cedex, France, and.
authors.forename: Abdelhak
authors.initials: A
authors.lastname: Fatihi
authors.affiliation: From the Institute for Genomics and Proteomics, University of California, Los Angeles, California 90095, the Department of Chemistry and Biochemistry, UCLA, Los Angeles, California 90095.
authors.forename: Stefan
authors.initials: S
authors.lastname: Schmollinger
authors.affiliation: the Horticultural Sciences Department, University of Florida, Gainesville, Florida 32611.
authors.forename: Gilles J
authors.initials: GJ
authors.lastname: Basset
authors.affiliation: From the Institute for Genomics and Proteomics, University of California, Los Angeles, California 90095, the Department of Chemistry and Biochemistry, UCLA, Los Angeles, California 90095, merchant@chem.ucla.edu.
authors.forename: Sabeeha S
authors.initials: SS
authors.lastname: Merchant
mesh_terms: D016825:Chlamydomonas reinhardtii / Q000235:genetics / Q000378:metabolism*; D002734:Chlorophyll / Q000096:biosynthesis* / Q000235:genetics; D002839:Chromans; D003300:Copper / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant / Q000502:physiology*; D010788:Photosynthesis / Q000502:physiology*; D010940:Plant Proteins / Q000096:biosynthesis / Q000235:genetics; D010971:Plastoquinone / Q000378:metabolism*; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D014810:Vitamin E / Q000031:analogs & derivatives* / Q000096:biosynthesis / Q000235:genetics
chemical_list: D002839:Chromans; D010940:Plant Proteins; D012333:RNA, Messenger; D014810:Vitamin E; D002734:Chlorophyll; C013649:plastochromanol 8; D003300:Copper; D010971:Plastoquinone
keywords: Chlamydomonas; LCAA; SBP domain; Ycf54; antioxidant; chlorophyll; light-harvesting complex (antenna complex); metal homeostasis