The Cytoplasmic and Periplasmic Expression Levels and Folding of Organophosphorus Hydrolase Enzyme in Escherichia coli

Background: Organophosphorus hydrolase (OPH) is a type of organophosphate-degrading enzyme which is widely used in the bioremediation process.

Objectives: In this study, the periplasmic and cytoplasmic productions and the activity of recombinant OPH in Escherichia coli were investigated and compared using two pET systems (pET21a and pET26b).

Materials and methods: The sequence encoding the opd gene was synthesized and expressed in the form of inclusion body using pET21a-opd and in the periplasmic space in pET26b-opd.

Results: Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) analysis showed a band of about 37 kDa with a maximum expression level at 30°C from pET21a-opd.However, the obtained results of the periplasmic space extraction of OPH (pET26b-opd) showed a very weak band, while the cytoplasmic expression of OPH (pET21a-opd) produced a strong protein band.

Conclusions: The activities studied by the production of PNP were determined by following the increase at 410 nm. The maximum PNP was produced at 30°C with an optical density of 10.62 in the presence of cytoplasmic expression of OPH (pET21a-opd). Consequently, our results suggest cytoplasmic expression system as an appropriate candidate with a high amount of OPH in spite of inclusion body formation, which needs an additional refolding step.