Analysis of the ptsH-ptsI-crr region in Escherichia coli K-12: evidence for the existence of a single transcriptional unit.

A cosmid containing the ptsH, ptsI and crr genes of Escherichia coli coding for three components of the phosphoenolpyruvate: sugar phosphotransferase system (PTS) has been isolated. The products of these genes were identified using the maxicell technique. The cloning of the PTS region as a whole allowed us to map and order ptsH, ptsI and crr genes in a 3.8-kb DNA fragment and determine that ptsI and crr are transcribed from a common promoter. They, therefore, constitute a single transcriptional unit which is likely to include also the ptsH gene. In addition, the crr gene may have a secondary promoter located inside ptsI.