Chloroplast remodeling during state transitions in Chlamydomonas reinhardtii as revealed by noninvasive techniques in vivo

• DOI: 10.1073/pnas.1322494111
• Publication Date: 2014-03-18T05:41:09Z
• Authors: Gergely Nagy; Renáta Ünnep; Ottó Zsiros; Ryutaro Tokutsu; Kenji Takizawa; Lionel Porcar; Lucas Moyet; Dimitris Petroutsos; Győző Garab; Giovanni Finazzi; Jun Minagawa
• Keywords: 0301 basic medicine; 570; Chloroplasts; [SDV.BBM]Life Sciences [q-bio]/Biochemistry; photosystem; protein-protein interactions; Light-Harvesting Protein Complexes; plant; Biochemistry; Models, Biological; Thylakoids; 03 medical and health sciences; Scattering, Small Angle; state transitions; [SDV.BV]Life Sciences [q-bio]/Vegetal Biology; [SDV.BBM]Life Sciences [q-bio]/Biochemistry, Molecular Biology; Photosynthesis; Molecular Biology; 580; light harvesting complex; photosynthesis; Photosystem I Protein Complex; Circular Dichroism; Photosystem II Protein Complex; thylakoid membrane; green algae; Neutron Diffraction; Q1 Science (General) / természettudomány általában; light acclimation mechanism; Mutation; Chlamydomonas reinhardtii

Significance

Oxygenic photosynthesis regulates light–energy conversion by balancing the activity of the two photosystems (PSs). Such a power balance requires a sophisticated regulatory mechanism called state transitions, which involve reversible phosphorylation of the light-harvesting complex proteins (LHCIIs) to redistribute absorbed excitation energy between the two photosystems. Using noninvasive techniques (small-angle neutron scattering, circular dichroism, and absorption transient spectroscopy) in the green alga Chlamydomonas reinhardtii , we have revealed that state transitions modify the chloroplast structure, affecting the stacking and periodicity of the photosynthetic membranes and altering protein–protein interactions within these membranes. These structural changes accompany the conversion of LHCII into an energy-dissipating mode with only minor displacements of phosphorylated LHCIIs from PSII to PSI, thereby allowing us to reevaluate the physiological significance of state transitions.