ULTRASTRUCTURE AND LIGHT ADAPTATION OF PHYCOBILISOME MUTANTS OF SYNECHOCYSTIS PCC-6803

We have performed functional and ultrastructural characterization of S ynechocystis PCC 6803 wild type and of two mutants, the first one (PMB 11) lacking phycocyanin and still possessing the core of the phycobili some and the second one (P Delta E) lacking phycocyanin and Lcm (the c ore membrane linker) and totally devoid of assembled phycobilisome str ucture. In the three strains, the state 1-state 2 transition occurred and was accompanied by ultrastructural changes. In state 1, an increas ed percentage of PS II-associated EF particles were aligned in rows co mpared to state 2 where more EF particles were randomly distributed in the membrane. A spill-over model is suggested by our ultrastructural and spectrophotometric results. (C) 1997 Elsevier Science B.V.