One of the major as yet unanswered questions with respect to synthesis and function of protein complexes in biological membranes is how these complexes assemble into functionally active entities. To address this question with respect to photosystem II (PS II), the convenient transformation system of the cyanobacterium Synechocystis sp. PCC 6803 is being utilized to create a number of PS II mutants containing site-directed mutations. Such mutants offer an excellent experimental system to determine the role cofactors (particularly quinones and chlorophylls) play in PS II assembly and stability. It is known from other systems that the presence of chlorophyll is a requirement for stability of chlorophyll-binding proteins, whereas in higher plants synthesis of one of the chlorophyll- binding in PS II appears to depend on the availability of chlorophyll. For this reason, mutations in presumed chlorophyll- binding residues are now introduced to investigate the effects on the synthesis and stability of the chlorophyll-binding proteins as well as of the entire PS II complex. With the Presidential Young Investigator Award, the study of the synthesis and function of photosystem II (PS II) of the photosynthetic apparatus is being significantly enhanced, thus contributing to a comprehensive insight into its involvement in photosynthesis.
