Optimization of gene expression in Streptomyces lividans by a transcription terminator.

The ability of an inverted repeat sequence (IRS) from the 3' end of the aph gene from Streptomyces fradiae to induce transcription termination in vivo has been examined. As a model system, a DNA fragment encoding the human interferon alpha 2 inserted in the Streptomyces plasmid pIJ702 was used. When the IRS was inserted downstream from this sequence and transcription assayed in Streptomyces lividans, highly efficient (approximately 90%) transcription termination was observed occurring immediately after the 3' terminus of the dyad. In contrast, gene constructions lacking the IRS transcribed longer mRNAs. Moreover, the IRS gave rise to increased amounts of the hIFN alpha 2 suggesting that the putative stem-loop structure stabilised the transcript.