Role of Phosphatidylglycerol in Oxygen-Evolving Complex of Photosystem II

Abstract

Properties Of Photosystem Ii (Psii) In The Pgsa Mutant Of Synechocystis Sp. Pcc6803, Which Is Defective For The Biosynthesis Of Phosphatidylglycerol (Pg), Were Analyzed To Clarify The Role Of Pg InOxygen-Evolving-Complex (Oec) Of Psii. Analyses Of Purified Psii Complexes Indicated That Psii From Pg-Depleted Pgsa Mutant Sustained Only 50% Of The Oxygen-Evolving Activity Compared To Wild-Type Cells And Dissociated The Extrinsic ProteinsOf Psbo, Psbv And Psbu, And Mn Ions. The Released Psbo Re-Bound To Psii When Pg Was Added Back To The Pg-Depleted Mutant Cells.The Extent Of Inactivation Of Oxygenevolution In The Pg-Depleted Mutant Cells By Heat Treatment Or Dark Incubation ResembledThose Of ▵Psbo And ▵Psbv Mutant Cells. These Results Suggest That Pg Plays An Important Role In The Binding Of Extrinsic Proteins Required For SustainingA Functional Mn-Cluster.