TY - JOUR
T1 - The Cyclization Mechanism of Cyclodextrin Glycosyltransferase (CGTase) as Revealed by a γ-Cyclodextrin-CGTase Complex at 1.8-Å Resolution
AU - Uitdehaag, Joost C.M.
AU - Kalk, Kor H.
AU - Veen, Bart A. van der
AU - Dijkhuizen, Lubbert
AU - Dijkstra, Bauke W.
N1 - Relation: http://www.rug.nl/gbb/
date_submitted:2009
Rights: University of Groningen, Groningen Biomolecular Sciences and Biotechnology Institute
PY - 1999/12/3
Y1 - 1999/12/3
N2 - The enzyme cyclodextrin glycosyltransferase is closely related to α-amylases but has the unique ability to produce cyclodextrins (circular α(1→4)-linked glucoses) from starch. To characterize this specificity we determined a 1.8-Å structure of an E257Q/D229N mutant cyclodextrin glycosyltransferase in complex with its product γ-cyclodextrin, which reveals for the first time how cyclodextrin is competently bound. Across subsites -2, -1, and +1, the cyclodextrin ring binds in a twisted mode similar to linear sugars, giving rise to deformation of its circular symmetry. At subsites -3 and +2, the cyclodextrin binds in a manner different from linear sugars. Sequence comparisons and site-directed mutagenesis experiments support the conclusion that subsites -3 and +2 confer the cyclization activity in addition to subsite -6 and Tyr-195. On this basis, a role of the individual residues during the cyclization reaction cycle is proposed.
AB - The enzyme cyclodextrin glycosyltransferase is closely related to α-amylases but has the unique ability to produce cyclodextrins (circular α(1→4)-linked glucoses) from starch. To characterize this specificity we determined a 1.8-Å structure of an E257Q/D229N mutant cyclodextrin glycosyltransferase in complex with its product γ-cyclodextrin, which reveals for the first time how cyclodextrin is competently bound. Across subsites -2, -1, and +1, the cyclodextrin ring binds in a twisted mode similar to linear sugars, giving rise to deformation of its circular symmetry. At subsites -3 and +2, the cyclodextrin binds in a manner different from linear sugars. Sequence comparisons and site-directed mutagenesis experiments support the conclusion that subsites -3 and +2 confer the cyclization activity in addition to subsite -6 and Tyr-195. On this basis, a role of the individual residues during the cyclization reaction cycle is proposed.
U2 - 10.1074/jbc.274.49.34868
DO - 10.1074/jbc.274.49.34868
M3 - Article
SN - 0021-9258
VL - 274
SP - 34868
EP - 34876
JO - The Journal of Biological Chemistry
JF - The Journal of Biological Chemistry
IS - 49
ER -