title: Nucleotide sequence and X-ray structure of cyclodextrin glycosyltransferase from Bacillus circulans strain 251 in a maltose-dependent crystal form.
abstract: The cyclodextrin glycosyltransferase (CGTase, EC 2.4.1.19) gene from Bacillus circulans strain 251 was cloned and sequenced. It was found to code for a mature protein of 686 amino acid residues, showing 75% identity to the CGTase from B. circulans strain 8. The X-ray structure of the CGTase was elucidated in a maltodextrin-dependent crystal form and refined against X-ray diffraction data to 2.0 A resolution. The structure of the enzyme is nearly identical to the CGTase from B. circulans strain 8. Three maltose binding sites are observed at the protein surface, two in domain E and one in domain C. The maltose-dependence of CGTase crystallization can be ascribed to the proximity of two of the maltose binding sites to intermolecular crystal contacts. The maltose molecules bound in the E domain interact with several residues implicated in a raw starch binding motif conserved among a diverse group of starch converting enzymes.
authors.affiliation: Laboratory of Biophysical Chemistry, University of Groningen, The Netherlands.
authors.forename: C L
authors.initials: CL
authors.lastname: Lawson
authors.forename: R
authors.initials: R
authors.lastname: van Montfort
authors.forename: B
authors.initials: B
authors.lastname: Strokopytov
authors.forename: H J
authors.initials: HJ
authors.lastname: Rozeboom
authors.forename: K H
authors.initials: KH
authors.lastname: Kalk
authors.forename: G E
authors.initials: GE
authors.lastname: de Vries
authors.forename: D
authors.initials: D
authors.lastname: Penninga
authors.forename: L
authors.initials: L
authors.lastname: Dijkhuizen
authors.forename: B W
authors.initials: BW
authors.lastname: Dijkstra
mesh_terms: D000595:Amino Acid Sequence; D001407:Bacillus / Q000201:enzymology*; D001483:Base Sequence; D001665:Binding Sites; D002240:Carbohydrate Sequence; D003001:Cloning, Molecular; D003196:Computer Graphics; D004269:DNA, Bacterial; D005964:Glucosyltransferases / Q000737:chemistry / Q000235:genetics*; D008320:Maltose / Q000378:metabolism*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011487:Protein Conformation; D014961:X-Ray Diffraction
chemical_list: D004269:DNA, Bacterial; D008320:Maltose; D005964:Glucosyltransferases; C019963:cyclomaltodextrin glucanotransferase