Design and construction of a synthetic Bacillus thuringiensis Cry4Aa gene: Hyperexpression in Escherichia coli

Tohru Hayakawa, Mohammad Tofazzal Hossain Howlader, Masashi Yamagiwa, Hiroshi Sakai

Research output: Contribution to journalArticlepeer-review

16 Citations (Scopus)


Cry4Aa produced by Bacillus thuringiensis is a dipteran-specific toxin and is, therefore, of great interest for developing a bioinsecticide to control mosquitoes. However, the expression of Cry4Aa in Escherichia coli is relatively low, which is a major disadvantage in its development as a bioinsecticide. In this study, to establish an effective production system, a 1,914-bp modified gene (cry4Aa-S1) encoding Cry4Aa was designed and synthesized in accordance with the G+C content and codon preference of E. coli genes without altering the encoded amino acid sequence. The cry4Aa-S1 gene allowed a significant improvement in expression level, over five-fold, compared to that of the original cry4Aa gene. The product of the cry4Aa-S1 gene showed the same level of insecticidal activity against Culex pipiens larvae as that from cry4Aa. This suggested that unfavorable codon usage was one of the reasons for poor expression of cry4Aa in E. coli, and, therefore, changing the cry4Aa codons to accord with the codon usage in E. coli led to efficient production of Cry4Aa. Efficient production of Cry4Aa in E. coli can be a powerful measure to prepare a sufficient amount of Cry4Aa protein for both basic analytical and applied researches.

Original languageEnglish
Pages (from-to)1033-1037
Number of pages5
JournalApplied Microbiology and Biotechnology
Issue number6
Publication statusPublished - Oct 2008


  • Bacillus thuringiensis
  • Bioinsecticide
  • Cry4Aa
  • Escherichia coli
  • Hyperexpression
  • Synthetic gene

ASJC Scopus subject areas

  • Biotechnology
  • Applied Microbiology and Biotechnology


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