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 d eficient in lipid fatty acid desaturation have been used in order to furthe r explore the influence of the modification of LHC II after mutation and pr oteolitic treatment on the energy transfer between the chlorophyll-protein complexes, as well as on the structure-function relationship in the supramo lecular complex of Photosystem II. The gaussian decomposition and analysis of the fluorescence bands associated with PS II complex show the controvers ial action of the trypsin in the investigated thylakoid membranes. This rev eals 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 demonstrat e that different amounts of oligomer and monomer forms of LHC II in the mut ants (LK3 and JB67), arising from lipid modification, are responsible for d ifferent proteolytic action in their thylakoid membranes. (C) 2000 Elsevier Science S.A. All rights reserved.