Repression of inducible enzyme synthesis in a mutant of Escherichia coli K12 deleted for the ptsH gene

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Abstract
The genome of γ phage with thermosensitive repressor was inserted into the pts region of the Escherichia coli chromosome. This lysogenic culture possessed the PTS 1 phenotype at 30°C. A mutant strain with a deletion covering the ptsH gene was isolated after a prophage curing procedure. The deletion nature of the pts mutation was confirmed in genetical and biochemical experiments. The deletion covered a small fragment of the bacterial genome not extending in the ptsI and lig genes. The isolated ΔptsH mutant possessed all characteristics of known pts mutants: pleiotropical disturbances of transport and utilization of a number of carbohydrates, repression of the enzyme inducible synthesis, and resistance to glucose catabolite repression. From these and other data we can conclude that the phosphorylated form of the heat-stable protein HPr is involved (directly or indirectly) in activation of the DNA transcription process.