Expression of the nopaline synthase gene in Escherichia coli.

The Agrobacterium tumor-inducing (Ti) plasmid pTiT37 encodes nopaline synthase (NOS) gene (nos) with eukaryotic promoter elements that is expressed in transformed plant cells but not in the bacterial host. We have fused the nos gene to the Escherichia coli trp promoter, and observed synthesis of NOS in E. coli. The nopaline produced by this enzyme is excreted into the culture medium. NOS is enzymatically active at 30 degrees C but not 37 degrees C, as based on nopaline production. NOS protein is produced at both temperatures, based on production in minicells.