Two Fructose 6-Phosphate Kinase Activities in Escherichia coli

An unlinked suppressor mutation, pfkB1,was reported to restore fructose 6-phosphate kinase activity to fructose 6-phosphate kinase mutants (e.g. pfkA1; Morrissey, A. T. E., andFraenkel, D. G. (1972) J. Bacteriol. 112, 183). We show here that a strain wild type at the pfkAlocus and also carrying the suppressor mutation contains two readily separable enzyme activities. Activity 1 resembles the known allosteric wild type enzyme, and activity 2 does not show allosteric characteristics.