Fructose-6-phosphate modifies the pathway of the urea-induced dissociation of the allosteric phosphofructokinase from Escherichia coli.
Phosphofructokinase from Escherichia coli binds fructose-6-phosphate with the sugar moiety of the substrate interacting with one subunit and the phosphate group with another one, so that bound fructose-6-phosphate lies across the interface between the subunits [(1988) J. Mol. Biol. 204, 973-994]. When this interface is 'cross-linked' by fructose-6-phosphate, it becomes more stable because of the extra interactions between subunits: inactivation upon dissociation occurs only above 5 M urea, instead of 1 M urea for the free protein. At saturation in fructose-6-phosphate, this interface is no longer the first to dissociate as in the free protein [(1989) Biochemistry 28, 6836-6841]: instead, the addition of urea to phosphofructokinase in the presence of fructose-6-phosphate induces a conformational change within the tetramer which alters the environment of Trp-311 and distorts the regulatory site.
Teschner
W
W
Laboratoire d'Enzymologie du CNRS, Gif-sur-Yvette, France.
Deville-Bonne
D
D
Garel
J R
JR
D000494:Allosteric Regulation; D004789:Enzyme Activation; D004926:Escherichia coli / Q000187:drug effects / Q000201:enzymology*; D005636:Fructosephosphates / Q000494:pharmacology*; D010732:Phosphofructokinase-1 / Q000378:metabolism*; D011487:Protein Conformation; D011489:Protein Denaturation; D013379:Substrate Specificity; D014508:Urea / Q000494:pharmacology*
D005636:Fructosephosphates; D014508:Urea; D010732:Phosphofructokinase-1