Isolation of Photosystem I Reaction Center Subunit K Gene GjPsaK from Gardenia Jasminoides

Objective: Photosystem I (PS I) is a large membrane supercomplex that consists of a reaction centre and light-harvesting complex (LHC I). PS I catalyzes lightdriven electron transport to produce reducing power NADPH, and then NADPH are used in the dark reactions of photosynthesis to fix CO2 and synthesize organic molecules. In this work, we will isolate gene of a reaction centre subunit Psak in Gardenia jasminoides. Methods: A Gardenia jasminoides fruit cDNA library was constructed, and the GjPsak cDNA was isolated from the cDNA library by sequencing method. Results: The cDNA was 593 bp in length, contains a predicted 393 bp ORF that encodes 130 amino acids, the gene was designated GjPsak The deduced amino acid sequence showed homology to PsaK from plants. A three-dimensional model of GjPsaK was built; the structure is similar to structures of Plant PsaK GjPsaK contains two transmembrane a-helices connected by a positively charged stromal loop; both the N and C termini are located in the luminal side of thylakoid membrane. Conclusion: According to functions of PsaK in plant, we implicated that the GjPsaK would involved in state transition and stabilization of LHC I organization.