Thylakoid conformational changes accompanying membrane protein phosphorylation

The effect of reversible membrane phosphorylation on the room temperature linear dichroism signal of magneto-oriented pea thylakoids was investigated. Membrane phosphorylation, induced by photoreduction of the plastoquinone pool, resulted in a change in the linear dichroism signal in the region of the red absorption band of chlorophyll. The optical change was due to modifications in selective polarized light scattering which have been shown to be indicative of alterations in the degree of membrane stacking. No changes in linear dichroism due to a reorientation of pigments were observed. It is concluded that phosphorylation of the membrane results in about a 10% destacking of the thylakoids and that this conformational change is implicated in energy redistribution between the two photosystems.