Molecular Cloning Of Gamma-amino Butyric Acid Synthase Gene From Oryza Sativa And Construction Of Prokaryotic Expression Vector

γ-Amino Butyric Acid (GABA), a non-protein amino acid, is a natural active constituent in some organisms. In animals, GABA serves as a neurotransmitter mediating more than 64 percent of inhibitory neurotransmition, systematically regulates brain blood vessel, enhances the function of human brain cell, and improves memory. Besides, GABA can also lower blood pressure, and function as an anti-anxiety substance, etc. While in plants, GABA is secondary metabolite and it can improve plant's resistance to pests. GABA synthase ( also named Glutamate decarboxylase, GAD) is the key enzyme of GABA synthesis pathway in plants.In this dissertation, with the technique of amplification of cDNA ends(RACE), a GABA synthase gene was isolated from the embryo of Oryza sativa L.SSP.indica"Xin-9-4" which was determined by the Institute of Agricultural Product Quality and contained high content of GABA. Sequence analysis, function prediction and construction of prokaryotic expression vector of the gene were also studied. The analyzing results of the gene are very helpful to elucidate its function validation, molecular evolution, and potential applications in crop quality genetic engineering. The major experiment results of this dissertation were as follows:1. Molecular cloning and characterization of GABA synthase gene. A couple of degenerate primers were designed according to the conserved amino acid sequence of different plants. A 751 bp length conserved fragment was cloned by RT-PCR, the full length cDNA was obtained later by RACE technique, and the obtained full length cDNA (1962 bp) contained an open reading frame (1479 bp) encoding 492 amino acids. This gene was named as Osgad, the molecular weight of its deduced polypeptide was 56 kDa. Identity analysis of the full length cDNA sequence shows 99% similarity with Oryza sativa (japonica cultivar-group) GABA synthase (GAD3) cDNA, 81% of that with Brassica juncea GABA synthase 4a (GAD4a) cDNA. The...