3N1C: Crystal Structure Of The Phosphofructokinase-2 From Escherichia Coli In Complex With Fructose-6-Phosphate

Substrate inhibition by ATP is a regulatory feature of the phosphofructokinases isoenzymes from Escherichia coli (Pfk-1 and Pfk-2). Under gluconeogenic conditions, the loss of this regulation in Pfk-2 causes substrate cycling of fructose-6-phosphate (fructose-6-P) and futile consumption of ATP delaying growth. In the present work, we have broached the mechanism of ATP-induced inhibition of Pfk-2 from both structural and kinetic perspectives. The crystal structure of Pfk-2 in complex with fructose-6-P is reported to a resolution of 2 A. The comparison of this structure with the previously reported inhibited form of the enzyme suggests a negative interplay between fructose-6-P binding and allosteric binding of MgATP. Initial velocity experiments show a linear increase of the apparent K(0.5) for fructose-6-P and a decrease in the apparent k(cat) as a function of MgATP concentration. These effects occur simultaneously with the induction of a sigmoidal kinetic behavior (n(H) of approximately 2). Differences and resemblances in the patterns of fructose-6-P binding and the mechanism of inhibition are discussed for Pfk-1 and Pfk-2, as an example of evolutionary convergence, because these enzymes do not share a common ancestor.
PDB ID: 3N1CDownload
MMDB ID: 87170
PDB Deposition Date: 2010/5/15
Updated in MMDB: 2010/12
Experimental Method:
x-ray diffraction
Resolution: 2  Å
Source Organism:
Similar Structures:
Biological Unit for 3N1C: tetrameric; determined by author and by software (PISA)
Molecular Components in 3N1C
Label Count Molecule
Proteins (4 molecules)
6-phosphofructokinase Isozyme 2(Gene symbol: pfkB)
Molecule annotation
Chemicals (4 molecules)
* Click molecule labels to explore molecular sequence information.

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