Expression Of Cptpi Gene From Spinach And Cfba Gene From Rice In Anabaena Sp. PCC 7120 And Its Regulation Of Photosynthesis

Photosynthesis is the most important chemic reaction in the world, and it is the ultimate energy source of any living organisms. The photosynthetic carbon reduction (Calvin) cycle is the primary pathway of carbon fixation in most photosynthetic life-form, and is the core reaction of photosynthesis regulation. A major goal in photosynthetic research is to identify limiting points in the process, in order to produce plants with increased yield.Calvin cycle is a complicated reaction system. It comprises 11 different enzymes, catalyzing 13 reactions, and can be divided into 3 phases: carboxylation, deoxidization and regeneration. Triosephosphate isomerase(TPI) and fructose-1,6-bisphosphate aldolase(FBA) serve as the first and the second enzymes in the regenerative phase of the Calvin cycle respectively. They catalyze two concatenated reactions. TPI catalyzes the interconversion of dihydroxyacetone phosphate and D-glyceraldehydes-3-phosphate. FBA catalyzes the reversible reaction that dihydroxyacetone phosphate and D-glyceraldehydes-3-phosphate are utilized to form fructose-6-phosphate. There are two branch points in Calvin cycle. The first point relates to DHAP, which can be transported into cytoplasm and gradually synthesize sucrose. Second point relates to fructose-6-phosphate, which can been gradually synthesize starch. So TPI and FBA are two important enzymes of Calvin cycle and may be exert significant control over the photosynthetic carbon flux. However, they were considered as "non-regulated enzyme", because they catalyze reversible reaction, and their regulations of carbon flux were always neglected. Over the last 10 years, antisense transgenic plants have been used as tools to address this and have revealed some unexpected findings.In this article, chloroplast tpi gene from spinach and tandem genes of chloroplast tpi gene from spinach and cytoplast fba gene from rice were transferred into filamentous, heterocystour cyanobacterium Anabaena sp. PCC 7120 using gene overexpress technology. The enzyme activity, growth parameters and photosynthesis activity were measured and compared between transgenic and wild type cells. The aim was to discuss the influence on photosynthesis as the level of TPI and FBA changed.The contents and results of this experiment were as follows:...