Characterization of Site-Directed and Hybrid psbC Mutants of Synechocystis 6803
Photosystem II (PS II) is composed of at least five integral membrane proteins (together forming the core complex), in addition to several peripheral polypeptides. CP43 is a chlorophyll-binding protein in the core complex that is involved in the transfer of excitation energy to the reaction center, and it is encoded by the gene psbC. In this study, specific mutagenesis has been applied to alter psbC in the transformable, photoheterotrophic cyanobacterium, Synechocystis 6803. By transforming psbC deletion mutants with altered psbC gene sequences, modified psbC can be directly incorporated into the organism’s genome by homologous recombination (1). PS II defective mutants can be propagated photoheterotrophically on media containing an appropriate carbon source such as glucose (2–6). In this report we compile our recent results concerning two issues that have lately been the focus of our interest in CP43: the identification of the translation start codon, and the functional dissection of the protein. We have addressed these issues using site-directed mutagenesis and chimeric gene strategies, respectively.
KeywordsCore Complex Translation Start Codon CP43 Protein Chlorophyll Basis Kanamycin Resistance Marker
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