RESUMEN
Nowadays, SUMO fusion system is important for recombinant protein production in Escherichia coli, yet a few aspects remain to be improved, including the efficacy for vector construction and protein solubility. In this study, we found the SUMO gene Smt3 (Sm) of Saccharomyces cerevisiae conferred an unexpected activity of constitutive prokaryotic promoter during its PCR cloning, and the gene coding regions of SUMOs in most species had a sigma70-dependent prokaryotic promoter embedded, through the prediction via the BPROM program developed by Softberry. By combining the characters of Sm promoter activity and the Stu I site (added at the 3'-terminal of Sm), and introducing a His-tag and a hyper-acidic solubility-enhancing tag, we further constructed a set of versatile vectors for gene cloning and expression on the basis of Sm'-LacZa fusion gene. Experimentally started from these vectors, several target genes were subcloned and expressed through blue-white screening and SDS-PAGE analysis. The results manifest a few of expectable advantages such as rapid vector construction, highly soluble protein expression and feasible co-expression of correlated proteins. Conclusively, our optimized SUMO fusion technology herein could confer a large potential in E. coli protein expression system, and the simultaneously established co-expression vector systems could also be very useful in studying the protein-protein interactions in vivo.