9J4I image
Entry Detail
PDB ID:
9J4I
Keywords:
Title:
Crystal structure of GH9l Inulin fructotransferases (IFTase) in compex with fruetosyl nystose (GF4)
Biological Source:
Host Organism:
PDB Version:
Deposition Date:
2024-08-09
Release Date:
2024-09-04
Method Details:
Experimental Method:
Resolution:
1.96 Å
R-Value Free:
0.18
R-Value Work:
0.15
R-Value Observed:
0.15
Space Group:
P 65
Macromolecular Entities
Polymer Type:polypeptide(L)
Description:DFA-III-forming inulin fructotransferase
Chain IDs:A, B, C
Chain Length:404
Number of Molecules:3
Biological Source:Paenarthrobacter aurescens
Primary Citation
Elucidation of the mechanism underlying the sequential catalysis of inulin by fructotransferase.
Int.J.Biol.Macromol. 277 134446 134446 (2024)
PMID: 39098696 DOI: 10.1016/j.ijbiomac.2024.134446

Abstact

Glycoside hydrolase family 91 (GH91) inulin fructotransferase (IFTases) enables biotransformation of fructans into sugar substitutes for dietary intervention in metabolic syndrome. However, the catalytic mechanism underlying the sequential biodegradation of inulin remains unelusive during the biotranformation of fructans. Herein we present the crystal structures of IFTase from Arthrobacter aurescens SK 8.001 in apo form and in complexes with kestose, nystose, or fructosyl nystose, respectively. Two kinds of conserved noncatalytic binding regions are first identified for IFTase-inulin interactions. The conserved interactions of substrates were revealed in the catalytic center that only contained a catalytic residue E205. A switching scaffold was comprised of D194 and Q217 in the catalytic channel, which served as the catalytic transition stabilizer through side chain displacement in the cycling of substrate sliding in/out the catalytic pocket. Such features in GH91 contribute to the catalytic model for consecutive cutting of substrate chain as well as product release in IFTase, and thus might be extended to other exo-active enzymes with an enclosed bottom of catalytic pocket. The study expands the current general catalytic principle in enzyme-substrate complexes and shed light on the rational design of IFTase for fructan biotransformation.

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