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Arabidopsis mutants deleted in the light-harvesting protein Lhcb4 have a disrupted photosystem II macrostructure and are defective in photoprotection.
- Source :
-
The Plant cell [Plant Cell] 2011 Jul; Vol. 23 (7), pp. 2659-79. Date of Electronic Publication: 2011 Jul 29. - Publication Year :
- 2011
-
Abstract
- The role of the light-harvesting complex Lhcb4 (CP29) in photosynthesis was investigated in Arabidopsis thaliana by characterizing knockout lines for each of the three Lhcb4 isoforms (Lhcb4.1/4.2/4.3). Plants lacking all isoforms (koLhcb4) showed a compensatory increase of Lhcb1 and a slightly reduced photosystem II/I ratio with respect to the wild type. The absence of Lhcb4 did not result in alteration in electron transport rates. However, the kinetic of state transition was faster in the mutant, and nonphotochemical quenching activity was lower in koLhcb4 plants with respect to either wild type or mutants retaining a single Lhcb4 isoform. KoLhcb4 plants were more sensitive to photoinhibition, while this effect was not observed in knockout lines for any other photosystem II antenna subunit. Ultrastructural analysis of thylakoid grana membranes showed a lower density of photosystem II complexes in koLhcb4. Moreover, analysis of isolated supercomplexes showed a different overall shape of the C₂S₂ particles due to a different binding mode of the S-trimer to the core complex. An empty space was observed within the photosystem II supercomplex at the Lhcb4 position, implying that the missing Lhcb4 was not replaced by other Lhc subunits. This suggests that Lhcb4 is unique among photosystem II antenna proteins and determinant for photosystem II macro-organization and photoprotection.
- Subjects :
- Arabidopsis Proteins genetics
Chlorophyll chemistry
Chlorophyll Binding Proteins genetics
Fluorescence
Gene Knockdown Techniques
Light
Lipid Peroxidation
Membrane Lipids chemistry
Membrane Lipids metabolism
Oxidation-Reduction
Oxidative Stress
Oxygen metabolism
Photosynthesis physiology
Photosynthetic Reaction Center Complex Proteins genetics
Photosynthetic Reaction Center Complex Proteins metabolism
Photosystem I Protein Complex metabolism
Photosystem II Protein Complex metabolism
Protein Isoforms genetics
Temperature
Thylakoids chemistry
Thylakoids metabolism
Thylakoids ultrastructure
Arabidopsis genetics
Arabidopsis physiology
Arabidopsis ultrastructure
Arabidopsis Proteins metabolism
Chlorophyll Binding Proteins metabolism
Photosystem II Protein Complex ultrastructure
Protein Isoforms metabolism
Subjects
Details
- Language :
- English
- ISSN :
- 1532-298X
- Volume :
- 23
- Issue :
- 7
- Database :
- MEDLINE
- Journal :
- The Plant cell
- Publication Type :
- Academic Journal
- Accession number :
- 21803939
- Full Text :
- https://doi.org/10.1105/tpc.111.087320