Structural highlights
Publication Abstract from PubMedCrystal structures of Klebsiella pneumoniae pullulanase (KPP) in complex with alpha-cyclodextrin (alpha-CD), beta-cyclodextrin (beta-CD) and gamma-cyclodextrin (gamma-CD) were refined at around 1.98-2.59 A resolution from data collected at SPring-8. In the structures of the complexes obtained with 1 mM alpha-CD or gamma-CD, one molecule of CD was found at carbohydrate-binding module 41 only (CBM41). In the structures of the complexes obtained with 1 mM beta-CD or with 10 mM alpha-CD or gamma-CD, two molecules of CD were found at CBM41 and in the active-site cleft, where the hydrophobic residue of Phe746 occupies the inside cavity of the CD rings. In contrast to alpha-CD and gamma-CD, one beta-CD molecule was found at the active site only in the presence of 0.1 mM beta-CD. These results were coincident with the solution experiments, which showed that beta-CD inhibits this enzyme more than a thousand times more potently than alpha-CD and gamma-CD. The strong inhibition of beta-CD is caused by the optimized interaction between beta-CD and the side chain of Phe746. The increased Ki values of the F746A mutant for beta-CD supported the importance of Phe746 in the strong interaction of pullulanase with beta-CD. Elucidation of the mechanism of interaction between Klebsiella pneumoniae pullulanase and cyclodextrin.,Saka N, Iwamoto H, Malle D, Takahashi N, Mizutani K, Mikami B Acta Crystallogr D Struct Biol. 2018 Nov 1;74(Pt 11):1115-1123. doi:, 10.1107/S2059798318014523. Epub 2018 Oct 30. PMID:30387770[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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