PMID: 17192265 , Related PDB ids: 2INU, 2INV

Authors:

Jung WS, Hong CK, Lee S, Kim CS, Kim SJ, Kim SI, Rhee S

Title:

Structural and functional insights into intramolecular fructosyl transfer by inulin fructotransferase.

Journal:

J Biol Chem. 2007 Mar 16;282(11):8414-23. Epub 2006 Dec 27.

Abstract:

Inulin fructotransferase (IFTase), a member of glycoside hydrolase family 91, catalyzes depolymerization of beta-2,1-fructans inulin by successively removing the terminal difructosaccharide units as cyclic anhydrides via intramolecular fructosyl transfer. The crystal structures of IFTase and its substrate-bound complex reveal that IFTase is a trimeric enzyme, and each monomer folds into a right-handed parallel beta-helix. Despite variation in the number and conformation of its beta-strands, the IFTase beta-helix has a structure that is largely reminiscent of other beta-helix structures but is unprecedented in that trimerization is a prerequisite for catalytic activity, and the active site is located at the monomer-monomer interface. Results from crystallographic studies and site-directed mutagenesis provide a structural basis for the exolytic-type activity of IFTase and a functional resemblance to inverting-type glycosyltransferases.