[Expression of the human alpha-1-antitrypsin gene in Escherichia coli]

The cDNA, containing the complete human alpha-1-antitrypsin (AT) sequence starting from codon 2, was used to construct bacterial strains producing AT. The fusion protein was obtained by junction of the AT cDNA to the fragment of an Escherichia coli ompF gene. We have also modified the AT cDNA's 5'-terminal part to construct DNAs containing ATG-codon and cDNA sequences starting from codons 1 or 2. These DNAs were inserted into E. coli expression vectors pBR322/trpII-8 and pKK223-3 that allow transcription from efficient trp- and tac-promoters. This construction resulted in the induction of a 46 kDa protein. The polypeptide produced was recognized by an antiserum raised against human alpha-1-antitrypsin protein. Truncation of the gene at its 5'-end or synthesis as a fusion OmpF-AT protein increases expression up to 10-fold, to a level of approximately 1%. On the contrary, no dependence on the promoter type has been observed. Physical properties of the recombinant proteins are discussed.