Evidence for a Role of VIPP1 in the Structural Organization of the Photosynthetic Apparatus in Chlamydomonas.

André Nordhues (1) , Mark Aurel Schöttler (1) , Ann-Katrin Unger (2) , Stefan Geimer (2) , Stephanie Schönfelder (3, 1) , Stefan Schmollinger (1) , Mark Rütgers (1) , Giovanni Finazzi (4) , Barbara Soppa (2) , Frederik Sommer (1) , Timo Mühlhaus (1) , Thomas Roach (5) , Anja Krieger-Liszkay (5) , Heiko Lokstein (3) , José Luis Crespo (6) , Michael Schroda (1, 7)

1 MPI-MP - Max Planck Institute of Molecular Plant Physiology
2 Zellbiologie/Elektronenmikroskopie
3 Institut für Biochemie und Biologie/Pflanzenphysiologie,
4 LPCV - Laboratoire de physiologie cellulaire végétale
5 SMPSD - Système membranaires, photobiologie, stress et détoxication
6 IBVF - Instituto de Bioquimica Vegetal y Fotosintesis
7 Fachbereich Biologie, Molekulare Biotechnologie und Systembiologie

The vesicle-inducing protein in plastids (VIPP1) was suggested to play a role in thylakoid membrane formation via membrane vesicles. As this functional assignment is under debate, we investigated the function of VIPP1 in Chlamydomonas reinhardtii. Using immunofluorescence, we localized VIPP1 to distinct spots within the chloroplast. In VIPP1-RNA interference/artificial microRNA cells, we consistently observed aberrant, prolamellar body-like structures at the origin of multiple thylakoid membrane layers, which appear to coincide with the immunofluorescent VIPP1 spots and suggest a defect in thylakoid membrane biogenesis. Accordingly, using quantitative shotgun proteomics, we found that unstressed vipp1 mutant cells accumulate 14 to 20% less photosystems, cytochrome b(6)f complex, and ATP synthase but 30% more light-harvesting complex II than control cells, while complex assembly, thylakoid membrane ultrastructure, and bulk lipid composition appeared unaltered. Photosystems in vipp1 mutants are sensitive to high light, which coincides with a lowered midpoint potential of the Q(A)/Q(A)(-) redox couple and increased thermosensitivity of photosystem II (PSII), suggesting structural defects in PSII. Moreover, swollen thylakoids, despite reduced membrane energization, in vipp1 mutants grown on ammonium suggest defects in the supermolecular organization of thylakoid membrane complexes. Overall, our data suggest a role of VIPP1 in the biogenesis/assembly of thylakoid membrane core complexes, most likely by supplying structural lipids.

Mots clés: Algae; Chlamydomonas; chloroplast; plastid; photosystem; lipid transport; thylakoid; membrane biogenesis; vesicle inducing protein; subcellular localization

Domaines: Biochimie, Biologie Moléculaire

André Nordhues, Mark Aurel Schöttler, Ann-Katrin Unger, Stefan Geimer, Stephanie Schönfelder, et al.. Evidence for a Role of VIPP1 in the Structural Organization of the Photosynthetic Apparatus in Chlamydomonas.. The Plant cell, 2012, 24 (2), pp.637-59. ⟨10.1105/tpc.111.092692⟩. ⟨hal-00675122⟩