4HE1

Crystal structure of human muscle fructose-1,6-bisphosphatase Q32R mutant complex with fructose-6-phosphate and phosphate

Summary for 4HE1

• Entry DOI: 10.2210/pdb4he1/pdb
• Related: 4HE0 4HE2
• Descriptor: Fructose-1,6-bisphosphatase isozyme 2, 6-O-phosphono-beta-D-fructofuranose, PHOSPHATE ION, ... (6 entities in total)
• Functional Keywords: allosteric enzyme, hydrolase
• Biological source: Homo sapiens (human)
• Cellular location: Cell junction : O00757
• Total number of polymer chains: 1
• Total formula weight: 37135.13

Authors

Shi, R.,Zhu, D.W.,Lin, S.X. (deposition date: 2012-10-03, release date: 2013-10-09, Last modification date: 2023-09-20)

Primary citation

Shi, R.,Chen, Z.Y.,Zhu, D.W.,Li, C.,Shan, Y.,Xu, G.,Lin, S.X.
Crystal Structures of Human Muscle Fructose-1,6-Bisphosphatase: Novel Quaternary States, Enhanced AMP Affinity, and Allosteric Signal Transmission Pathway.
Plos One, 8:e71242-e71242, 2013

PubMed Abstract: Fructose-1,6-bisphosphatase, a key enzyme in gluconeogenesis, is subject to metabolic regulation. The human muscle isozyme is significantly more sensitive towards the allosteric inhibitor, AMP, than the liver isoform. Here we report crystal structures and kinetic studies for wild-type human muscle Fru-1,6-Pase, the AMP-bound (1.6 Å), and product-bound complexes of the Q32R mutant, which was firstly introduced by an error in the cloning. Our high-resolution structure reveals for the first time that the higher sensitivity of the muscle isozyme towards AMP originates from an additional water-mediated, H-bonded network established between AMP and the binding pocket. Also present in our structures are a metaphosphate molecule, alternate conformations of Glu97 coordinating Mg(2+), and possible metal migration during catalysis. Although the individual subunit is similar to previously reported Fru-1,6-Pase structures, the tetrameric assembly of all these structures deviates from the canonical R- or T-states, representing novel tetrameric assemblies. Intriguingly, the concentration of AMP required for 50% inhibition of the Q32R mutant is increased 19-fold, and the cooperativity of both AMP and Mg(2+) is abolished or decreased. These structures demonstrate the Q32R mutation affects the conformations of both N-terminal residues and the dynamic loop 52-72. Also importantly, structural comparison indicates that this mutation in helix α2 is detrimental to the R-to-T conversion as evidenced by the absence of quaternary structural changes upon AMP binding, providing direct evidence for the critical role of helix α2 in the allosteric signal transduction.

PubMed: 24086250
DOI: 10.1371/journal.pone.0071242

Experimental method

X-RAY DIFFRACTION (2.23 Å)