Cloning, expression, and partial characterization of FBPA from Schistosoma japonicum , a molecule on that the fluke may develop nutrition competition and immune evasion from human

Carbohydrate metabolism is the most important physiological process for Schistosoma japonicum which resides in host. However, as a key glycolytic enzyme in carbohydrate metabolism, fructose-1,6- bis phosphate aldolase (FBPA), there is no study on its enzymatic kinetics and antigenic peptides. Here, we report the gene cloning, expression, purification, and kinetics of the FBPA from S. japonicum ( sj FBPA). After cloning, sj FBPA gene was introduced into pET-28a and transformed BL21, and a soluble His 6 - sj FBPA was expressed and purified successfully at the expected molecular mass of ~45 kDa. We first reported that the diversities in IGS regions and the features of residues position 346 and 357–362 of sj FBPA may be conferred either through conformational changes influencing easily the active site from a distance and/or causing the C-terminal region to interact directly with the active site, which lead His 6 - sj FBPA to exhibit a higher specific activity of 197.43 units/mg and degrades FBP with a typical substrate inhibition model and a higher efficiency of k cat = 6261.3/s and K m = 0.061 μM than human aldolases, which might be the strategy that S. japonicum gaining energy and surviving in its environment with low concentration of carbohydrate, and benefitting to get more metabolic substances for parasites in nutrition competition with their host. sj FBPA exhibits a high similarity of 81.46 % with that of hosts, especially in antigenic peptide regions, and 14 of 15 antigenic peptides of sj FBPA were conserved to those of human aldolase A, B, and/or C with high identity (17, 16, or 16 antigenic peptides, respectively), which may result in a molecular mimicry of FBPA with that of host, and an immune evasion from their hosts. This work would supply an experimental base for using FBPA to prevent the schistosomiasis in the future.