E. coli K-12 pel mutants, which block phage lambda DNA injection, coincide with ptsM, which determines a component of...

Escherichia coli pel- mutants inhibit the penetration of bacteriophage lambda DNA into the cell. Using P1 mediated cotransduction, we mapped pel- mutations between markers fadD and eda in the interval of minute 40 of the revised E. coli K-12 map. This places pel in the same region as genes kdgR and ptsM. Mutations in kdgR usually do not alter the Pel phenotype, and vice versa. In contrast, about 30% of ptsM- mutants are also pel-, and all pel- mutants isolated are ptsM-. These results suggest that pel and ptsM are one and the same gene. This interpretation would identify the bacterial product required for injection of phage lambda DNA as a component of the phosphoenolpyruvate-dependent phosphotransferase system specific for mannose, glucosamine, glucose and fructose. However, the experimental results do not exclude an alternative explanation: that pel and ptsM identify two closely linked genes which would be simultaneously affected at high frequency by a particular mutational event.