The possible relationship between a membrane conformational change and photosystem II dependent hydrogen ion...

Data are presented which suggest that photosystem II dependent hydrogen ion accumulation and ATP synthesis can occur only after the lamellar membranes have undergone a conformational change. This membrane conformational change is detected by the electron transport dependent incorporation of diazonium benzene[35S]sulfonate into membrane components. Previously it was established that electron flux from the photosystem II primary acceptor to plastoquinone is a necessary event for the occurrence of the diazonium-detected conformational change. These studies indicate that the release of hydrogen ions during photosystem II oxidation of the primary reductant is also a necessary event for the diazonium-detected conformational change. When iodide were substituted for water (or other proton-releasing donors) as the primary reductant of system II the conformational change did not occur even though a substantial rate of electron flow from the primary acceptor to plastoquinone occurred.