Background & Objectives: Uropathogenic Escherichia coli (UPEC) is one of the most common bacteria to cause urinary tract infection (UTI). No human vaccine against UTI has yet been developed. The aim of this study was to optimize the expression of recombinant PapG with Lactobacillus anchor protein AcmA in E. coli. Materials & Methods: The synthetic cloning vector, pEXA containing PapG.AcmA was purchased and subcloned into pET21a vector. The protein expression levels in Origami expression host (E. coli) were analyzed by SDS-PAGE gel and western blotting. Moreover, various concentrations of IPTG (Isopropyl Thiogalactopyranoside), the medium component and induction time was optimized for large scale expression of recombinant protein. Results: Based on results, optimum expression in large scale was occurred in 0.1mM IPTG and OD= 3 optical density. The modified complex culture medium containing: glucose 6 g/I, K2HPO4 12.5 g/l, KH2PO4 2.3 g/l, Yeast Extract 20 g/l, tryptone 10 g/l were determined as optimal medium. OD 600nm= 3.0 was determined as the best time for induction by IPTG at a concentration of 0.1 mM. The levels of the expression of the target protein was determined at OD600nm= 5.5. Conclusion: Based on the result, we were able to do cloning and expression of PapG.AcmA. Addition of extra carbon source (glucose) to the complex medium caused a better PapG.AcmA recombinant protein expression. Finally, by purification of recombinant protein and evaluation of its immunogenicity, it can be used as a vaccine candidate against the urinary tract infection.
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