title: Crystal structure of beta-helical antifreeze protein points to a general ice binding model.
abstract: Reported here is the 2.3 A resolution crystal structure of spruce budworm (Choristoneura fumiferana) antifreeze protein (CfAFP), solved by single anomalous scattering. The structure reveals an extremely regular left-handed beta-helical platform consisting of 15-amino acid loops with a repetitive Thr-X-Thr motif displayed on one of the helix's three faces. This motif results in a two-dimensional array of threonine residues in an identical orientation to those in the nonhomologous, right-handed beta-helical beetle AFP from Tenebrio molitor (TmAFP). The CfAFP structure led us to reevaluate our ice binding model, and the analysis of three possible modes of docking gives rise to a binding mechanism based on surface complementarity. This general mechanism is applicable to both fish and insect AFPs.
authors.affiliation: Department of Biochemistry, Queen's University, Kingston, Ontario K7L 3N6, Canada.
authors.forename: Eeva K
authors.initials: EK
authors.lastname: Leinala
authors.forename: Peter L
authors.initials: PL
authors.lastname: Davies
authors.forename: Zongchao
authors.initials: Z
authors.lastname: Jia
mesh_terms: D000818:Animals; D021301:Antifreeze Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D018360:Crystallography, X-Ray; D019281:Dimerization; D005399:Fishes / Q000378:metabolism; D006860:Hydrogen Bonding; D007053:Ice; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D015394:Molecular Structure; D009036:Moths / Q000737:chemistry*; D011485:Protein Binding; D017433:Protein Structure, Secondary; D013912:Threonine / Q000737:chemistry
chemical_list: D021301:Antifreeze Proteins; D007053:Ice; D013912:Threonine