Organization of the Escherichia coli chromosome around the genes for translation initiation factor IF2 (infB) and a transcription termination factor (nusA)

The genes infB, for translational initiation factor IF2, and nusA for a protein involved in transcription termination are carried on a 4.8 X 10(3) base-pair DNA fragment. This fragment also carries promoters capable of expressing both genes. The order of these genes with respect to the surrounding genes is pnp, rpsO, infB, nusA, argG. Transcription of the two genes is anticlockwise on the standard Escherichia coli map, i.e. directed towards the genes rpsO and pnp. The presence of infB on multicopy plasmids enhances IF2 protein and messenger RNA levels only two to threefold compared to the normal haploid level.