1EYJ

FRUCTOSE-1,6-BISPHOSPHATASE COMPLEX WITH AMP, MAGNESIUM, FRUCTOSE-6-PHOSPHATE AND PHOSPHATE (T-STATE)

Summary for 1EYJ

• Entry DOI: 10.2210/pdb1eyj/pdb
• Related: 1CNQ 1EYI 1EYK
• Descriptor: FRUCTOSE-1,6-BISPHOSPHATASE, 6-O-phosphono-beta-D-fructofuranose, MAGNESIUM ION, ... (6 entities in total)
• Functional Keywords: bisphosphatase, allosteric enzymes, gluconeogenesis, hydrolase
• Biological source: Sus scrofa (pig)
• Total number of polymer chains: 2
• Total formula weight: 74835.68

Authors

Choe, J.,Honzatko, R.B. (deposition date: 2000-05-07, release date: 2000-08-09, Last modification date: 2024-02-07)

Primary citation

Choe, J.Y.,Fromm, H.J.,Honzatko, R.B.
Crystal structures of fructose 1,6-bisphosphatase: mechanism of catalysis and allosteric inhibition revealed in product complexes.
Biochemistry, 39:8565-8574, 2000

PubMed Abstract: Crystal structures of metal-product complexes of fructose 1, 6-bisphosphatase (FBPase) reveal competition between AMP and divalent cations. In the presence of AMP, the Zn(2+)-product and Mg(2+)-product complexes have a divalent cation present only at one of three metal binding sites (site 1). The enzyme is in the T-state conformation with a disordered loop of residues 52-72 (loop 52-72). In the absence of AMP, the enzyme crystallizes in the R-state conformation, with loop 52-72 associated with the active site. In structures without AMP, three metal-binding sites are occupied by Zn(2+) and two of three metal sites (sites 1 and 2) by Mg(2+). Evidently, the association of AMP with FBPase disorders loop 52-72, the consequence of which is the release of cations from two of three metal binding sites. In the Mg(2+) complexes (but not the Zn(2+) complexes), the 1-OH group of fructose 6-phosphate (F6P) coordinates to the metal at site 1 and is oriented for a nucleophilic attack on the bound phosphate molecule. A mechanism is presented for the forward reaction, in which Asp74 and Glu98 together generate a hydroxide anion coordinated to the Mg(2+) at site 2, which then displaces F6P. Development of negative charge on the 1-oxygen of F6P is stabilized by its coordination to the Mg(2+) at site 1.

PubMed: 10913263
DOI: 10.1021/bi000574g

Experimental method

X-RAY DIFFRACTION (2.28 Å)