title: Three-dimensional structure of an intact glycoside hydrolase family 15 glucoamylase from Hypocrea jecorina.
abstract: The three-dimensional structure of a complete Hypocrea jecorina glucoamylase has been determined at 1.8 A resolution. The presented structure model includes the catalytic and starch binding domains and traces the course of the 37-residue linker segment. While the structures of other fungal and yeast glucoamylase catalytic and starch binding domains have been determined separately, this is the first intact structure that allows visualization of the juxtaposition of the starch binding domain relative to the catalytic domain. The detailed interactions we see between the catalytic and starch binding domains are confirmed in a second independent structure determination of the enzyme in a second crystal form. This second structure model exhibits an identical conformation compared to the first structure model, which suggests that the H. jecorina glucoamylase structure we report is independent of crystal lattice contact restraints and represents the three-dimensional structure found in solution. The proposed starch binding regions for the starch binding domain are aligned with the catalytic domain in the three-dimensional structure in a manner that supports the hypothesis that the starch binding domain serves to target the glucoamylase at sites where the starch granular matrix is disrupted and where the enzyme might most effectively function.
authors.affiliation: Genencor-A Danisco Division, 925 Page Mill Road, Palo Alto, California 94304, USA. rick.bott@danisco.com
authors.forename: Richard
authors.initials: R
authors.lastname: Bott
authors.forename: Mae
authors.initials: M
authors.lastname: Saldajeno
authors.forename: William
authors.initials: W
authors.lastname: Cuevas
authors.forename: Donald
authors.initials: D
authors.lastname: Ward
authors.forename: Martijn
authors.initials: M
authors.lastname: Scheffers
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Aehle
authors.forename: Saeid
authors.initials: S
authors.lastname: Karkehabadi
authors.forename: Mats
authors.initials: M
authors.lastname: Sandgren
authors.forename: Henrik
authors.initials: H
authors.lastname: Hansson
mesh_terms: D001665:Binding Sites; D002384:Catalysis; D020134:Catalytic Domain; D018360:Crystallography, X-Ray; D005087:Glucan 1,4-alpha-Glucosidase / Q000737:chemistry*; D006860:Hydrogen Bonding; D035901:Hypocrea / Q000201:enzymology*; D007700:Kinetics; D008958:Models, Molecular; D011485:Protein Binding; D011487:Protein Conformation; D017510:Protein Folding; D017434:Protein Structure, Tertiary
chemical_list: D005087:Glucan 1,4-alpha-Glucosidase