High level expression of porcine growth hormone in Escherichia coli from an expression vector containing bacteriophage lambda PL and N gene untranslated region.

An Escherichia coli expression vector, pG408N containing a PL promoter and the upstream untranslated region of the N gene of bacteriophage lambda has been constructed. We have designed a PvuII site immediately behind the untranslated region. A DNA fragment starting with an initiation codon ATG could be inserted into this site for expression. This vector also contains 7 additional cloning sites downstream from the PvuII site. A gene could be cloned into one of these sites and the 5' sequence of this gene could be modified with synthetic oligonucleotides and ligated to the PvuII for the purpose of increasing gene expression. We have also cloned the lambda cl gene into a p15A plasmid. Cotransformation of this plasmid with the expression vector allows the cloning vector pG408N to be used in any E. coli strain. Using this system, we were able to express porcine growth hormone to approximately 35% of total proteins in E. coli DH5 alpha.