2i1v
From Proteopedia
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Crystal structure of PFKFB3 in complex with ADP and Fructose-2,6-bisphosphate
Overview
To understand the molecular basis of a phosphoryl transfer reaction, catalyzed by the 6-phosphofructo-2-kinase domain of the hypoxia-inducible, bifunctional enzyme 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase, (PFKFB3), the crystal structures of PFKFB3AMPPCPfructose-6-phosphate and, PFKFB3ADPphosphoenolpyruvate complexes were determined to 2.7 A and 2.25 A, resolution, respectively. Kinetic studies on the wild-type and, site-directed mutant proteins were carried out to confirm the structural, observations. The experimentally varied liganding states in the active, pocket cause no significant conformational changes. In the, pseudo-substrate complex, a strong direct interaction between AMPPCP and, fructose-6-phosphate (Fru-6-P) is found. By virtue of this direct, substrate-substrate interaction, Fru-6-P is aligned with AMPPCP in an, orientation and proximity most suitable for a direct transfer of the, gamma-phosphate moiety to 2-OH of Fru-6-P. The three key atoms involved in, the phosphoryl transfer, the beta,gamma-phosphate bridge oxygen atom, the, gamma-phosphorus atom, and the 2-OH group are positioned in a single line, suggesting a direct phosphoryl transfer without formation of a, phosphoenzyme intermediate. In addition, the distance between 2-OH and, gamma-phosphorus allows the gamma-phosphate oxygen atoms to serve as a, general base catalyst to induce an "associative" phosphoryl transfer, mechanism. The site-directed mutant study and inhibition kinetics suggest, that this reaction will be catalyzed most efficiently by the protein when, the substrates bind to the active pocket in an ordered manner in which ATP, binds first.
About this Structure
2I1V is a Single protein structure of sequence from Homo sapiens with , , and as ligands. Full crystallographic information is available from OCA.
Reference
A Direct Substrate-Substrate Interaction Found in the Kinase Domain of the Bifunctional Enzyme, 6-Phosphofructo-2-kinase/Fructose-2,6-bisphosphatase., Kim SG, Cavalier M, El-Maghrabi MR, Lee YH, J Mol Biol. 2007 Jun 29;370(1):14-26. Epub 2007 Mar 21. PMID:17499765
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