Improvement of soluble recombinant interferon-α expression by methyl α-D-glucopyranoside in araBAD promoter system of Escherichia coli

To improve the soluble expression of recombinant human interferon-α that was directed by the araBAD promoter system of Escherichia coli, we attempted to control the overall protein expression rate via the addition of a repressor, methyl α-D-glucospyranoside (α-MG). Recombinant interferon-α was usually expressed as an inclusion body at the end of DO (dissolved oxygen)-stat fed-batch culture. However, the addition of 0.0025 to 0.01% α-MG after 0.5% L-arabinose induction effectively inhibited a tendency towards the formation of inclusion bodies, in which 67.6 to 73.1% of the expressed interferon-α was found in the soluble fraction. It was likely that the addition of a repressor after L-arabinose induction partially modulated the transcription rate from the araBAD promoter system and changed the ratio of soluble and insoluble interferon-α expression. This modulation might be considered as a method that can improve the soluble expression level of recombinant protein at the optimal temperature for cell growth.