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Crystal structure of heart 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase (PFKFB2) and the inhibitory influence of citrate on substrate binding

Journal Article · · Proteins
DOI:https://doi.org/10.1002/prot.25204· OSTI ID:1430308
 [1];  [1];  [1];  [1];  [2];  [3];  [1]
  1. Louisiana State Univ., Baton Rouge, LA (United States)
  2. Korea Research Inst. of Bioscience and Biotechnology, Daejeon (Korea)
  3. Cornell Univ., Argonne, IL (United States)
+ Show Author Affiliations
The heart–specific isoform of 6–phosphofructo–2–kinase/fructose–2,6–bisphosphatase (PFKFB2) is an important regulator of glycolytic flux in cardiac cells. Here, we present the crystal structures of two PFKFB2 orthologues, human and bovine, at resolutions of 2.0 and 1.8 Å, respectively. Citrate, a TCA cycle intermediate and well–known inhibitor of PFKFB2, co–crystallized in the 2–kinase domains of both orthologues, occupying the fructose–6–phosphate binding–site and extending into the γ–phosphate binding pocket of ATP. Furthermore, this steric and electrostatic occlusion of the γ–phosphate site by citrate proved highly consequential to the binding of cocomplexed ATP analogues. The bovine structure, which co–crystallized with ADP, closely resembled the overall structure of other PFKFB isoforms, with ADP mimicking the catalytic binding mode of ATP. The human structure, on the other hand, co–complexed with AMPPNP, which, unlike ADP, contains a γ–phosphate. The presence of this γ–phosphate made adoption of the catalytic ATP binding mode impossible for AMPPNP, forcing the analogue to bind atypically with concomitant conformational changes to the ATP binding–pocket. Inhibition kinetics were used to validate the structural observations, confirming citrate's inhibition mechanism as competitive for F6P and noncompetitive for ATP. Together, these structural and kinetic data establish a molecular basis for citrate's negative feed–back loop of the glycolytic pathway via PFKFB2.
Research Organization:
Argonne National Laboratory (ANL), Argonne, IL (United States)
Sponsoring Organization:
USDOE Office of Science (SC)
OSTI ID:
1430308
Journal Information:
Proteins, Journal Name: Proteins Journal Issue: 1 Vol. 85; ISSN 0887-3585
Publisher:
WileyCopyright Statement
Country of Publication:
United States
Language:
ENGLISH

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Cited By (3)

Citrate targets FBPase and constitutes an emerging novel approach for cancer therapy journal November 2018
Molecular adaptations to phosphorus deprivation and comparison with nitrogen deprivation responses in the diatom Phaeodactylum tricornutum journal February 2018
Fructose 2,6-Bisphosphate in Cancer Cell Metabolism journal September 2018

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Related Subjects

59 BASIC BIOLOGICAL SCIENCES
6-Phosphofructo-2-kinase/Fructose-2
6-bisphosphatase
PFKFB2
cardiac
citrate
crystal structure
fructose-2
6-bisphosphate
glycolysis
heart
inhibition