Lack of the light-harvesting complex CP24 affects the structure and function of the grana membranes of higher plant chloroplasts.
2006 (English)In: The Plant Cell, ISSN 1040-4651, E-ISSN 1532-298X, Vol. 18, no 11, 3106-20 p.Article in journal (Refereed) Published
The photosystem II (PSII) light-harvesting antenna in higher plants contains a number of highly conserved gene products whose function is unknown. Arabidopsis thaliana plants depleted of one of these, the CP24 light-harvesting complex, have been analyzed. CP24-deficient plants showed a decrease in light-limited photosynthetic rate and growth, but the pigment and protein content of the thylakoid membranes were otherwise almost unchanged. However, there was a major change in the macroorganization of PSII within these membranes; electron microscopy and image analysis revealed the complete absence of the C2S2M2 light-harvesting complex II (LHCII)/PSII supercomplex predominant in wild-type plants. Instead, only C2S2 supercomplexes, which are deficient in the LHCIIb M-trimers, were found. Spectroscopic analysis confirmed the disruption of the wild-type macroorganization of PSII. It was found that the functions of the PSII antenna were disturbed: connectivity between PSII centers was reduced, and maximum photochemical yield was lowered; rapidly reversible nonphotochemical quenching was inhibited; and the state transitions were altered kinetically. CP24 is therefore an important factor in determining the structure and function of the PSII light-harvesting antenna, providing the linker for association of the M-trimer into the PSII complex, allowing a specific macroorganization that is necessary both for maximum quantum efficiency and for photoprotective dissipation of excess excitation energy.
Place, publisher, year, edition, pages
2006. Vol. 18, no 11, 3106-20 p.
Arabidopsis/*metabolism/radiation effects/ultrastructure, Arabidopsis Proteins/analysis/isolation & purification/*metabolism, Chloroplasts/*ultrastructure, Chromatography; Gel, Circular Dichroism, DNA; Bacterial/metabolism, Fluorescence, Light, Light-Harvesting Protein Complexes/analysis/*deficiency/isolation & purification, Models; Biological, Mutagenesis; Insertional, Photosynthesis/radiation effects, Photosynthetic Reaction Center Complex Proteins/metabolism, Photosystem II Protein Complex/metabolism, Pigments; Biological/metabolism, Plant Leaves/radiation effects, RNA; Antisense/metabolism, Structure-Activity Relationship, Temperature, Thylakoids/*ultrastructure
IdentifiersURN: urn:nbn:se:umu:diva-14197DOI: 10.1105/tpc.106.045641PubMedID: 17114352OAI: oai:DiVA.org:umu-14197DiVA: diva2:153868