Uncoupling the MgATP-induced inhibition and aggregation of Escherichia coli phosphofructokinase-2 by C-terminal mutations

Binding of MgATP to an allosteric site of Escherichia coli phosphofructokinase-2 (Pfk-2) provoked inhibition and a dimer–tetramer (D–T) conversion of the enzyme. Successive deletions of up to 10 residues and point mutations at the C-terminal end led to mutants with elevated KMapp values for MgATP which failed to show the D–T conversion, but were still inhibited by the nucleotide. Y306 was required for the quaternary packing involved in the D–T conversion and the next residue, L307, was crucial for the ternary packing necessary for the catalytic MgATP-binding site. These results show that the D–T conversion could be uncoupled from the conformational changes that lead to the MgATP-induced allosteric inhibition.