ISOLATION AND PROPERTIES OF ESCHERICHIA-C OLI K12 MUTANTS WITHOUT PSEUDO-HPR ACTIVITY OF THE FRUCTOSE TRANSFER SYSTEM

Mutants without pseudo-HPr activity intrinsic to the H domain of the F ruB protein were obtained in Escherichia coli K12 through insertional mutagenesis by means of the Mudllac phage and TnPhoA transposon, For i solating these mutants, double mutants of enteric bacterium (ptsH fruR or ptsH fruS) were used as original strains. These double mutants wer e inactive with respect to the total HPr protein of the phosphoenolpyr uvate-carbohydrate phosphotransferase system and could not provide con stitutive synthesis of fructose-specific proteins of this system. The mutants obtained were designated fruH, mapped, and genetically charact erized. Insertions were shown to be located in exactly the portion of the fruB gene that specifies synthesis of the H domain of the FruB pro tein. The fruH mutations decreased motility of bacteria both in a medi um free of carbohydrates and in a medium with glucose, fructose, or ma ltose. In addition, fruH mutants with the Mudllac genome insertion had sharply decreased activity of beta-galactosidase.