title: Hyperactive antifreeze proteins from longhorn beetles: some structural insights.
abstract: This study reports on structural characteristics of hyperactive antifreeze proteins (AFPs) from two species of longhorn beetles. In Rhagium mordax, eight unique mRNAs coding for five different mature AFPs were identified from cold-hardy individuals. These AFPs are apparently homologues to a previously characterized AFP from the closely related species Rhagium inquisitor, and consist of six identifiable repeats of a putative ice binding motif TxTxTxT spaced irregularly apart by segments varying in length from 13 to 20 residues. Circular dichroism spectra show that the AFPs from both species have a high content of β-sheet and low levels of α-helix and random coil. Theoretical predictions of residue-specific secondary structure locate these β-sheets within the putative ice-binding motifs and the central parts of the segments separating them, consistent with an overall β-helical structure with the ice-binding motifs stacked in a β-sheet on one side of the coil. Molecular dynamics models based on these findings show that these AFPs would be energetically stable in a β-helical conformation.
authors.affiliation: Institute of Science, Systems and Models, Roskilde University Center, DK-4000 Roskilde, Denmark.
authors.forename: Erlend
authors.initials: E
authors.lastname: Kristiansen
authors.forename: Casper
authors.initials: C
authors.lastname: Wilkens
authors.forename: Bjarne
authors.initials: B
authors.lastname: Vincents
authors.forename: Dennis
authors.initials: D
authors.lastname: Friis
authors.forename: Anders Blomkild
authors.initials: AB
authors.lastname: Lorentzen
authors.forename: Håvard
authors.initials: H
authors.lastname: Jenssen
authors.forename: Anders
authors.initials: A
authors.lastname: Løbner-Olesen
authors.forename: Hans
authors.initials: H
authors.lastname: Ramløv
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D021301:Antifreeze Proteins / Q000737:chemistry* / Q000302:isolation & purification; D001517:Coleoptera / Q000737:chemistry*; D019476:Insect Proteins / Q000737:chemistry* / Q000302:isolation & purification; D056004:Molecular Dynamics Simulation; D008969:Molecular Sequence Data; D020033:Protein Isoforms; D017422:Sequence Analysis, DNA
chemical_list: D021301:Antifreeze Proteins; D019476:Insect Proteins; D020033:Protein Isoforms