• Gene expression;
  • GC-rich DNA;
  • Leader open reading frame;
  • Extreme thermophile;
  • Thermus thermophilus;
  • Escherichia coli;
  • Promoter tac

Abstract To improve expression efficiency of the leuB gene of an extreme thermophile, Thermus thermophilus, in Escherichia coli, the gene was placed under a potent promoter, tac. However, the expression was hardly improved, despite increased transcription. The expression under tac promoter was significantly improved by introducing a leader open reading frame in front of the gene. Similar improvement under a weak promoter, tet, with a leader open reading frame had been described previously. The present results provide evidence that the major limiting step in the expression of a GC-rich thermophile gene in E. coli is translation, and that the addition of a leader open reading frame is more crucial for high level expression of the gene than the use of a potent promoter.