Identification of the ice-binding face of a plant antifreeze protein.
The antifreeze protein of Lolium perenne, a perennial ryegrass, was previously modeled as a beta-roll with two extensive flat beta-sheets on opposite sides of the molecule. Here we have validated the model with a series of nine site-directed steric mutations in which outward-pointing short side-chain residues were replaced by tyrosine. None of these disrupted the fold. Mutations on one of the beta-sheets and on the sides of the protein retained 70% or greater activity. Three mutations that clustered on the other flat surface lost up to 90% of their antifreeze activity and identify this beta-sheet as the ice-binding face.
Middleton
Adam J
AJ
Department of Biochemistry, Queen's University, Kingston, Ontario, Canada K7L 3N6.
Brown
Alan M
AM
Davies
Peter L
PL
Walker
Virginia K
VK
D000595:Amino Acid Sequence; D021301:Antifreeze Proteins / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D001665:Binding Sites / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics; D057927:Hydrophobic and Hydrophilic Interactions; D008129:Lolium / Q000235:genetics / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding / Q000235:genetics; D017510:Protein Folding; D017433:Protein Structure, Secondary; D015203:Reproducibility of Results; D017386:Sequence Homology, Amino Acid; D013499:Surface Properties; D014443:Tyrosine / Q000378:metabolism
D021301:Antifreeze Proteins; D010940:Plant Proteins; D014443:Tyrosine