title: The Evolutionarily Conserved Protein PHOTOSYNTHESIS AFFECTED MUTANT71 Is Required for Efficient Manganese Uptake at the Thylakoid Membrane in Arabidopsis.
abstract: In plants, algae, and cyanobacteria, photosystem II (PSII) catalyzes the light-driven oxidation of water. The oxygen-evolving complex of PSII is a Mn4CaO5 cluster embedded in a well-defined protein environment in the thylakoid membrane. However, transport of manganese and calcium into the thylakoid lumen remains poorly understood. Here, we show that Arabidopsis thaliana PHOTOSYNTHESIS AFFECTED MUTANT71 (PAM71) is an integral thylakoid membrane protein involved in Mn(2+) and Ca(2+) homeostasis in chloroplasts. This protein is required for normal operation of the oxygen-evolving complex (as evidenced by oxygen evolution rates) and for manganese incorporation. Manganese binding to PSII was severely reduced in pam71 thylakoids, particularly in PSII supercomplexes. In cation partitioning assays with intact chloroplasts, Mn(2+) and Ca(2+) ions were differently sequestered in pam71, with Ca(2+) enriched in pam71 thylakoids relative to the wild type. The changes in Ca(2+) homeostasis were accompanied by an increased contribution of the transmembrane electrical potential to the proton motive force across the thylakoid membrane. PSII activity in pam71 plants and the corresponding Chlamydomonas reinhardtii mutant cgld1 was restored by supplementation with Mn(2+), but not Ca(2+) Furthermore, PAM71 suppressed the Mn(2+)-sensitive phenotype of the yeast mutant Δpmr1 Therefore, PAM71 presumably functions in Mn(2+) uptake into thylakoids to ensure optimal PSII performance.
authors.affiliation: Molekularbiologie der Pflanzen (Botanik), Department Biologie I, Ludwig-Maximilians-Universität München, 82152 Martinsried, Germany anja.schneider@lrz.uni-muenchen.de.
authors.forename: Anja
authors.identifier: 0000-0002-3377-5825
authors.initials: A
authors.lastname: Schneider
authors.affiliation: Molekularbiologie der Pflanzen (Botanik), Department Biologie I, Ludwig-Maximilians-Universität München, 82152 Martinsried, Germany.
authors.forename: Iris
authors.initials: I
authors.lastname: Steinberger
authors.affiliation: Department of Biological and Environmental Sciences, University of Gothenburg, 40530 Gothenburg, Sweden.
authors.forename: Andrei
authors.initials: A
authors.lastname: Herdean
authors.affiliation: Molekularbiologie der Pflanzen (Botanik), Department Biologie I, Ludwig-Maximilians-Universität München, 82152 Martinsried, Germany.
authors.forename: Chiara
authors.initials: C
authors.lastname: Gandini
authors.affiliation: Institut für Biochemie der Pflanzen, Cluster of Excellence on Plant Science, Heinrich-Heine-Universität Düsseldorf, 40225 Düsseldorf, Germany.
authors.forename: Marion
authors.identifier: 0000-0002-2743-8630
authors.initials: M
authors.lastname: Eisenhut
authors.affiliation: Institut für Biochemie der Pflanzen, Cluster of Excellence on Plant Science, Heinrich-Heine-Universität Düsseldorf, 40225 Düsseldorf, Germany.
authors.forename: Samantha
authors.identifier: 0000-0002-6853-1399
authors.initials: S
authors.lastname: Kurz
authors.affiliation: Molekularbiologie der Pflanzen (Botanik), Department Biologie I, Ludwig-Maximilians-Universität München, 82152 Martinsried, Germany.
authors.forename: Anna
authors.identifier: 0000-0002-5696-7224
authors.initials: A
authors.lastname: Morper
authors.affiliation: Molekularbiologie der Pflanzen (Botanik), Department Biologie I, Ludwig-Maximilians-Universität München, 82152 Martinsried, Germany.
authors.forename: Natalie
authors.identifier: 0000-0002-5776-7072
authors.initials: N
authors.lastname: Hoecker
authors.affiliation: Molekularbiologie der Pflanzen (Botanik), Department Biologie I, Ludwig-Maximilians-Universität München, 82152 Martinsried, Germany.
authors.forename: Thilo
authors.identifier: 0000-0003-0155-2168
authors.initials: T
authors.lastname: Rühle
authors.affiliation: Molekularbiologie der Pflanzen (Botanik), Department Biologie I, Ludwig-Maximilians-Universität München, 82152 Martinsried, Germany.
authors.forename: Mathias
authors.initials: M
authors.lastname: Labs
authors.affiliation: Biozentrum Köln, Botanisches Institut der Universität zu Köln, Lehrstuhl II, 50674 Köln, Germany.
authors.forename: Ulf-Ingo
authors.initials: UI
authors.lastname: Flügge
authors.affiliation: Zellbiologie/Elektronenmikroskopie NW I/B1, Universität Bayreuth, 95447 Bayreuth, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Geimer
authors.affiliation: Plant and Soil Science Section, Department of Plant and Environmental Sciences, Faculty of Science, University of Copenhagen, 1871 Frederiksberg C, Denmark.
authors.forename: Sidsel Birkelund
authors.initials: SB
authors.lastname: Schmidt
authors.affiliation: Plant and Soil Science Section, Department of Plant and Environmental Sciences, Faculty of Science, University of Copenhagen, 1871 Frederiksberg C, Denmark.
authors.forename: Søren
authors.initials: S
authors.lastname: Husted
authors.affiliation: Institut für Biochemie der Pflanzen, Cluster of Excellence on Plant Science, Heinrich-Heine-Universität Düsseldorf, 40225 Düsseldorf, Germany.
authors.forename: Andreas P M
authors.identifier: 0000-0003-0970-4672
authors.initials: AP
authors.lastname: Weber
authors.affiliation: Department of Biological and Environmental Sciences, University of Gothenburg, 40530 Gothenburg, Sweden.
authors.forename: Cornelia
authors.initials: C
authors.lastname: Spetea
authors.affiliation: Molekularbiologie der Pflanzen (Botanik), Department Biologie I, Ludwig-Maximilians-Universität München, 82152 Martinsried, Germany Copenhagen Plant Science Centre, University of Copenhagen, 1871 Frederiksberg, Denmark.
authors.forename: Dario
authors.initials: D
authors.lastname: Leister
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism; D016825:Chlamydomonas reinhardtii / Q000235:genetics / Q000378:metabolism; D002736:Chloroplasts / Q000378:metabolism; D008345:Manganese / Q000378:metabolism*; D060431:Thylakoid Membrane Proteins / Q000378:metabolism*; D020524:Thylakoids / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; D060431:Thylakoid Membrane Proteins; D008345:Manganese; D002118:Calcium