Deletion Mapping of the Genes Coding for HPr and Enzyme I of the Phosphoenolpyruvate: Sugar Phosphotransferase System in Salmonella typhimurium

Sugars transported by a bacterial phosphoenolpyruvate:sugar phosphotransferase system (PTS) require two soluble proteins: HPr, a low-molecular-weight phosphate-carrier protein, and enzyme I. The structural genes coding for HPr ( ptsH ) and Enzyme I ( ptsI ) are shown to be cotransducible in Salmonella typhimurium . The gene order of this region of the Salmonella chromosome is cysA-trzA-ptsH-ptsI ...( crr ). A method for the isolation of trzA-pts deletion is described. One class of pts deletions extends through ptsH and into ptsI ; a second class includes both ptsH and ptsI and extends into or through the crr gene. The crr gene either codes for or regulates the synthesis of a third PTS protein (factor III) which is sugar-specific. A hypothesis is presented for a mechanism of deletion formation.