Effect of promoter strength and signal sequence on the periplasmic expression of human interferon- &#9452b in Escherichia coli

Two plasmids, pFLAG-ATS and pET 26b(+), were studied for the periplasmic expression of recombinant human interferon-2b (IFN-2b) in Escherichia coli. The pFLAG-ATS contains ompA signal sequence and tac promoter while pET 26b(+) contains pelB signal sequence and T7lac promoter. It was observedthat periplasmic expression of IFN-2b from pET 26b(+) was around 3000 times higher than pFLAGATS. Difference in the expression level was attributed to the difference in the promoters and the signal sequences. In silico analysis of mRNA secondary structures were analyzed using Vienna RNA packageand MFOLD. The results suggested that the increase of expression would mainly due to the difference in the translation initiation associated with secondary structure of mRNA transcribed by both plasmids