Effect of modification of light-harvesting complex II on fluorescence properties of thylakoid membranes of Arabidopsis thaliana

The 77 K chlorophyll fluorescence spectra of Arabidopsis thaliana mutants deficient in lipid fatty acid desaturation have been used in order to further explore the influence of the modification of LHC II after mutation and proteolitic treatment on the energy transfer between the chlorophyll-protein complexes, as well as on the structure-function relationship in the supramolecular complex of Photosystem II. The gaussian decomposition and analysis of the fluorescence bands associated with PS II complex show the controversial action of the trypsin in the investigated thylakoid membranes. This reveals that the organization of PS II complexes is different in the wild type and both mutants indicating altered connection between the LHC II and the RC core complexes of PS II in both mutants. The results obtained demonstrate that different amounts of oligomer and monomer forms of LHC II in the mutants (LK3 and JB67), arising from lipid modification, are responsible for different proteolytic action in their thylakoid membranes.