1EO7

BACILLUS CIRCULANS STRAIN 251 CYCLODEXTRIN GLYCOSYLTRANSFERASE IN COMPLEX WITH MALTOHEXAOSE

Summary for 1EO7

• Entry DOI: 10.2210/pdb1eo7/pdb
• Related: 1CDG 1CXF 1CXK 1CXL 1D3C 1EO5
• Related PRD ID: PRD_900009 PRD_900010 PRD_900035
• Descriptor: PROTEIN (CYCLODEXTRIN GLYCOSYLTRANSFERASE), alpha-D-glucopyranose-(1-4)-alpha-D-glucopyranose-(1-4)-alpha-D-glucopyranose-(1-4)-alpha-D-glucopyranose-(1-4)-alpha-D-glucopyranose-(1-4)-alpha-D-glucopyranose, alpha-D-glucopyranose-(1-4)-alpha-D-glucopyranose-(1-4)-alpha-D-glucopyranose, ... (6 entities in total)
• Functional Keywords: alpha-amylase, maltohexaose, oligosaccharide, family 13 glycosyl hydrolase, transglycosylation, induced fit, catalysis, transferase, cyclodextrin
• Biological source: Bacillus circulans
• Total number of polymer chains: 1
• Total formula weight: 77243.92

Authors

Uitdehaag, J.C.M.,Dijkstra, B.W. (deposition date: 2000-03-22, release date: 2000-11-22, Last modification date: 2024-11-20)

Primary citation

Uitdehaag, J.C.,van Alebeek, G.J.,van Der Veen, B.A.,Dijkhuizen, L.,Dijkstra, B.W.
Structures of maltohexaose and maltoheptaose bound at the donor sites of cyclodextrin glycosyltransferase give insight into the mechanisms of transglycosylation activity and cyclodextrin size specificity.
Biochemistry, 39:7772-7780, 2000

PubMed Abstract: The enzymes from the alpha-amylase family all share a similar alpha-retaining catalytic mechanism but can have different reaction and product specificities. One family member, cyclodextrin glycosyltransferase (CGTase), has an uncommonly high transglycosylation activity and is able to form cyclodextrins. We have determined the 2.0 and 2.5 A X-ray structures of E257A/D229A CGTase in complex with maltoheptaose and maltohexaose. Both sugars are bound at the donor subsites of the active site and the acceptor subsites are empty. These structures mimic a reaction stage in which a covalent enzyme-sugar intermediate awaits binding of an acceptor molecule. Comparison of these structures with CGTase-substrate and CGTase-product complexes reveals three different conformational states for the CGTase active site that are characterized by different orientations of the centrally located residue Tyr 195. In the maltoheptaose and maltohexaose-complexed conformation, CGTase hinders binding of an acceptor sugar at subsite +1, which suggests an induced-fit mechanism that could explain the transglycosylation activity of CGTase. In addition, the maltoheptaose and maltohexaose complexes give insight into the cyclodextrin size specificity of CGTases, since they precede alpha-cyclodextrin (six glucoses) and beta-cyclodextrin (seven glucoses) formation, respectively. Both ligands show conformational differences at specific sugar binding subsites, suggesting that these determine cyclodextrin product size specificity, which is confirmed by site-directed mutagenesis experiments.

PubMed: 10869182
DOI: 10.1021/bi000340x

Experimental method

X-RAY DIFFRACTION (2.48 Å)