Changes in the composition of the photosynthetic apparatus in the galactolipid-deficient dgd1 mutant of Arabidopsis thaliana.
The glycerolipid digalactosyl diacylglycerol (DGDG) is exclusively associated with photosynthetic membranes and thus may play a role in the proper assembly and maintenance of the photosynthetic apparatus. Here we employ a genetic approach based on the dgd1 mutant of Arabidopsis thaliana to investigate the function of DGDG in thylakoid membranes. The primary defect in the genetically well-characterized dgd1 mutant resulted in a 90% reduction of the DGDG content. The mutant showed a decreased photosystem II (PSII) to photosystem I ratio. In vivo room- and low-temperature (77 K) chlorophyll fluorescence measurements with thylakoid preparations are in agreement with a drastically altered excitation energy allocation to the reaction centers. Quantification of pigment-binding apoproteins and pigments supports an altered stoichiometry of individual pigment-protein complexes in the mutant. Most strikingly, an increase in the amount of peripheral light-harvesting complexes of PSII relative to the inner antenna complexes and the PSII reaction center/core complexes was observed. Regardless of the severe alterations in thylakoid organization, photosynthetic oxygen evolution was virtually not compromised in dgd1 mutant leaves.
Härtel
H
H
Institut für Genbiologische Forschung Berlin GmbH, Germany.
Lokstein
H
H
Dörmann
P
P
Grimm
B
B
Benning
C
C
D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D038983:Galactolipids; D006017:Glycolipids / Q000172:deficiency / Q000235:genetics*; D045342:Light-Harvesting Protein Complexes; D009154:Mutation; D010788:Photosynthesis; D045322:Photosynthetic Reaction Center Complex Proteins / Q000378:metabolism*; D045331:Photosystem I Protein Complex; D045332:Photosystem II Protein Complex; D010860:Pigments, Biological / Q000378:metabolism; D018515:Plant Leaves / Q000254:growth & development; D011485:Protein Binding; D013050:Spectrometry, Fluorescence
D038983:Galactolipids; D006017:Glycolipids; D045342:Light-Harvesting Protein Complexes; D045322:Photosynthetic Reaction Center Complex Proteins; D045331:Photosystem I Protein Complex; D045332:Photosystem II Protein Complex; D010860:Pigments, Biological