The Research On The Functions Of The Important Subunit In Photosystem Reaction Centers In Synechocystis Sp. PCC6803

Cyanobacteria are prokaryotic organisms that, like green plants, perform oxygenic photosynthesis using two photosystems. Light energy is absorbed by large protein complexes on the surface of the thylakoid membrane called phycobilisomes. The phycobilisomes then transfer and apportion energy to the reaction centres.With the development of molecular biology and molecular genetics, especially DNA recombinant, The cyanobacteria molecular genetics makes a great progress in modern biotechnology. One side is to provide the method for cyanobacteria photosynthesis research, the other side is accelerating the application of cyanobacteria gene engineering on production.Synechocystis sp. PCC6803 is the first phototroph to have its complete genomic sequence determined. This spontaneously transformable cyanobacterium can incorporate foreign DNA into its genome by homologous recombination. This character is convenient for the experiment.Through molecular biology technique, the gene apcD and apcF was amplified by PCR. apcD was deleted and replaced by an kanamycin resistance cassette to generate plasmid and apcF was insert with kanamycin resistance cassette in the middle , which were used to transform the Synechocystis sp. PCC6803 wild-type strain. By resistance screening, the mutant-type strain with kanamycin resistance was obtained. Compared to the wild-type, the mutant-type growed slower, phycobiliproteins, chlorophyll A and soluble proteins contained in the mutant-type are less than the wild-type. Results from UV-Vis absorption spectra showed that the photosynthetic pigment components of the mutant-type is the same to the the wild-type but differ in quantity.We concluded that the disruption of apcD has effects on the energy transfer from the phycobilisomes to the reaction centres. Because the apcD gene is just a spur track among the systerm,so the mutant-type can still grow.