Suppression of growth defects of α-amylase secreting Escherichia coli by signal sequence fusion

Research output: Contribution to journalArticle


Two fusions of the Bacillus stearothermophilus α-amylase gene (amyS) with lacpoZ′ were constructed. The first, being a transcriptional fusion, placed amyS directly under lac promoter control eliminating interference by the endogenous promoter. IPTG induction of amyS transcription in this construction resulted in liberation of periplasmic proteins and eventually cell lysis. The other fusion replaced eight N-terminal amino acid residues from the signal sequence by 11 residues from the lacZ′ moiety in pUC-18. Translation initiation signals were also replaced by those from lacpoZ′. In this case IPTG induction resulted in secretion of approx. 35% of total α-amylase activity in the growth medium after 24 h growth without detectable cell lysis.


External organisations
  • University of Turku
  • University of Helsinki
Research areas and keywords


  • Bacillus stearothermophilus, Escherichia coli, Periplasmic protein, Protein secretion, α-amylase
Original languageEnglish
Pages (from-to)3-7
Number of pages5
JournalFEMS Microbiology Letters
Issue number1
Publication statusPublished - 1988
Publication categoryResearch
Externally publishedYes