title: Role of galactolipid biosynthesis in coordinated development of photosynthetic complexes and thylakoid membranes during chloroplast biogenesis in Arabidopsis.
abstract: The galactolipids monogalactosyldiacylglycerol (MGDG) and digalactosyldiacylglycerol (DGDG) are the predominant lipids in thylakoid membranes and indispensable for photosynthesis. Among the three isoforms that catalyze MGDG synthesis in Arabidopsis thaliana, MGD1 is responsible for most galactolipid synthesis in chloroplasts, whereas MGD2 and MGD3 are required for DGDG accumulation during phosphate (Pi) starvation. A null mutant of Arabidopsis MGD1 (mgd1-2), which lacks both galactolipids and shows a severe defect in chloroplast biogenesis under nutrient-sufficient conditions, accumulated large amounts of DGDG, with a strong induction of MGD2/3 expression, during Pi starvation. In plastids of Pi-starved mgd1-2 leaves, biogenesis of thylakoid-like internal membranes, occasionally associated with invagination of the inner envelope, was observed, together with chlorophyll accumulation. Moreover, the mutant accumulated photosynthetic membrane proteins upon Pi starvation, indicating a compensation for MGD1 deficiency by Pi stress-induced galactolipid biosynthesis. However, photosynthetic activity in the mutant was still abolished, and light-harvesting/photosystem core complexes were improperly formed, suggesting a requirement for MGDG for proper assembly of these complexes. During Pi starvation, distribution of plastid nucleoids changed concomitantly with internal membrane biogenesis in the mgd1-2 mutant. Moreover, the reduced expression of nuclear- and plastid-encoded photosynthetic genes observed in the mgd1-2 mutant under Pi-sufficient conditions was restored after Pi starvation. In contrast, Pi starvation had no such positive effects in mutants lacking chlorophyll biosynthesis. These observations demonstrate that galactolipid biosynthesis and subsequent membrane biogenesis inside the plastid strongly influence nucleoid distribution and the expression of both plastid- and nuclear-encoded photosynthetic genes, independently of photosynthesis.
authors.affiliation: Graduate School of Arts and Sciences, University of Tokyo, Komaba 3-8-1, Tokyo, 153-8902, Japan.|RIKEN Plant Science Center, 1-7-22 Suehiro-cho, Tsurumi, Yokohama, Kanagawa, 230-0045, Japan.
authors.forename: Koichi
authors.initials: K
authors.lastname: Kobayashi
authors.affiliation: Center for Biological Resources and Informatics, Tokyo Institute of Technology, 4259-B-65 Nagatsuta-cho, Yokohama, 226-8501, Midori-ku, Japan.
authors.forename: Takafumi
authors.initials: T
authors.lastname: Narise
authors.affiliation: Faculty of Education and Integrated Arts and Sciences, Waseda University, 2-2 Wakamatsu-cho, Tokyo, 162-8480, Shinjuku-ku, Japan.
authors.forename: Kintake
authors.initials: K
authors.lastname: Sonoike
authors.affiliation: Graduate School of Arts and Sciences, University of Tokyo, Komaba 3-8-1, Tokyo, 153-8902, Japan.
authors.forename: Haruki
authors.initials: H
authors.lastname: Hashimoto
authors.affiliation: Graduate School of Arts and Sciences, University of Tokyo, Komaba 3-8-1, Tokyo, 153-8902, Japan.
authors.forename: Naoki
authors.initials: N
authors.lastname: Sato
authors.affiliation: Department of Cell Biology, National Institute for Basic Biology, Okazaki, 444-8585, Japan.
authors.forename: Maki
authors.initials: M
authors.lastname: Kondo
authors.affiliation: Department of Cell Biology, National Institute for Basic Biology, Okazaki, 444-8585, Japan.
authors.forename: Mikio
authors.initials: M
authors.lastname: Nishimura
authors.affiliation: RIKEN Plant Science Center, 1-7-22 Suehiro-cho, Tsurumi, Yokohama, Kanagawa, 230-0045, Japan.
authors.forename: Mayuko
authors.initials: M
authors.lastname: Sato
authors.affiliation: RIKEN Plant Science Center, 1-7-22 Suehiro-cho, Tsurumi, Yokohama, Kanagawa, 230-0045, Japan.
authors.forename: Kiminori
authors.initials: K
authors.lastname: Toyooka
authors.affiliation: RIKEN Plant Science Center, 1-7-22 Suehiro-cho, Tsurumi, Yokohama, Kanagawa, 230-0045, Japan.
authors.forename: Keiko
authors.initials: K
authors.lastname: Sugimoto
authors.affiliation: Graduate School of Arts and Sciences, University of Tokyo, Komaba 3-8-1, Tokyo, 153-8902, Japan.
authors.forename: Hajime
authors.initials: H
authors.lastname: Wada
authors.affiliation: Graduate School of Arts and Sciences, University of Tokyo, Komaba 3-8-1, Tokyo, 153-8902, Japan.
authors.forename: Tatsuru
authors.initials: T
authors.lastname: Masuda
authors.affiliation: Center for Biological Resources and Informatics, Tokyo Institute of Technology, 4259-B-65 Nagatsuta-cho, Yokohama, 226-8501, Midori-ku, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Ohta
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins; D002736:Chloroplasts / Q000502:physiology*; D038983:Galactolipids / Q000096:biosynthesis*; D018506:Gene Expression Regulation, Plant / Q000502:physiology; D008563:Membrane Lipids / Q000378:metabolism; D010788:Photosynthesis; D045322:Photosynthetic Reaction Center Complex Proteins / Q000502:physiology*; D020524:Thylakoids / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; D038983:Galactolipids; D008563:Membrane Lipids; D045322:Photosynthetic Reaction Center Complex Proteins; C007388:digalactosyldiacylglycerol; C009909:monogalactosyldiacylglycerol