Identification, Characterization And Functional Analysis Of Gene All1723 Product From The Anabaena Sp. Strain PCC 7120

Anabaena sp. PCC 7120 is a filamentous cyanobacteria with vegetative cells and heterocysts. Vegetative cells are for photosynthesis while heterocysts are for nitrogen fixation. So Anabaena sp. PCC 7120 is often used as one of the type species to research the photosynthesis and nitrogen fixation. The physiological, biochemical characteristics and genetic backgrounds of Anabaena sp. PCC 7120 are relatively clear because of its simple life style and long-term history of human cultured. After Kazusa DNA Research Institute completed the whole genome sequencing of Anabaena sp. PCC 7120 in 2001, the genomic research began. Much of the functional gene product was determined. However, there is still a part of gene that has not been identified, such as gene all1723. With bioinformatics, the product of the gene is predicted as a possible aldolase.Carbon–carbon bond formation is one of the most important reactions for organic chemistry. The enzymes catalyze carbon–carbon bond formation are used as biocatalysts in organic reactions because of their ability to catalyze stereoselective reactions. In this area, aldol condensations catalyzed by aldolases are widely used in the synthesis of sugars, polyhydroxy antibiotics, and many other biologically active compounds. Therefore, aldolases are increasingly attractive as biocatalysts and especially important for carbohydrate biosynthesis. Among the most studied representatives of this group enzymes are fructose-1,6-bisphosphate aldolases. Fructose-1,6-bisphosphate aldolase catalyzes the reversible aldol condensation of dihydroxyacetonephosphate (DHAP) and glyceraldehyde 3-phosphate (GAP) in Calvin cycle, glycolysis and gluconeogenesis. In Calvin cycle, it catalyzes the compounds from 3C to 6C after CO2 fixation. It is at the first branch point and at the same time, it is also important to control the rate of photosynthesis.Secondly, it also participated in the glycolysis reaction with the opposite role that catalyzed the compounds from 3C to 6C. It is also involved in gluconeogenesis, pentose phosphate ways, and it is one of the key enzyme in the organisms with aerobic and anaerobic glycolysis metabolism.This study first identified the product of gene all1723 in Anabaena sp. PCC 7120 as a fructose-1, 6-diphosphate aldolase, and then studied its characterizations and function. The results as follows: The product of gene all1723 is a class II fructose-1,6-bisphosphate aldolase by bioinformatics and experiment; the optimum conditions of the activity of product of gene all1723 is pH8.0, added 0.2mM Mg2+ ,but its activity can be inhibited by 1mM EDTA; the mutant of all1723M & all1723O was obtained, which can do the further research of the all1723 function analysis.