3lih | pdb_00003lih
Crystal structure of fructosyltransferase (D191A) from A. japonicus in complex with raffinose
Structural highlights
Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedFructosyltransferases catalyze the transfer of a fructose unit from one sucrose/fructan to another and are engaged in the production of fructooligosaccharide/fructan. The enzymes belong to the glycoside hydrolase family 32 (GH32) with a retaining catalytic mechanism. Here we describe the crystal structures of recombinant fructosyltransferase (AjFT) from Aspergillus japonicus CB05 and its mutant D191A complexes with various donor/acceptor substrates, including sucrose, 1-kestose, nystose, and raffinose. This is the first structure of fructosyltransferase of the GH32 with a high transfructosylation activity. The structure of AjFT comprises two domains with an N-terminal catalytic domain containing a five-blade beta-propeller fold linked to a C-terminal beta-sandwich domain. Structures of various mutant AjFT-substrate complexes reveal complete four substrate-binding subsites (-1 to +3) in the catalytic pocket with shapes and characters distinct from those of clan GH-J enzymes. Residues Asp-60, Asp-191, and Glu-292 that are proposed for nucleophile, transition-state stabilizer, and general acid/base catalyst, respectively, govern the binding of the terminal fructose at the -1 subsite and the catalytic reaction. Mutants D60A, D191A, and E292A completely lost their activities. Residues Ile-143, Arg-190, Glu-292, Glu-318, and His-332 combine the hydrophobic Phe-118 and Tyr-369 to define the +1 subsite for its preference of fructosyl and glucosyl moieties. Ile-143 and Gln-327 define the +2 subsite for raffinose, whereas Tyr-404 and Glu-405 define the +2 and +3 subsites for inulin-type substrates with higher structural flexibilities. Structural geometries of 1-kestose, nystose and raffinose are different from previous data. All results shed light on the catalytic mechanism and substrate recognition of AjFT and other clan GH-J fructosyltransferases. Crystal structures of Aspergillus japonicus fructosyltransferase complex with donor/acceptor substrates reveal complete subsites in the active site for catalysis.,Chuankhayan P, Hsieh CY, Huang YC, Hsieh YY, Guan HH, Hsieh YC, Tien YC, Chen CD, Chiang CM, Chen CJ J Biol Chem. 2010 Jul 23;285(30):23251-64. Epub 2010 May 13. PMID:20466731[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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