title: Solution structures of a 30-residue amino-terminal domain of the carp granulin-1 protein and its amino-terminally truncated 3-30 subfragment: implications for the conformational stability of the stack of two beta-hairpins.
abstract: Carp granulins are members of an emerging class of proteins with a sequence motif encoding a parallel stack of two to four beta-hairpins. The carp granulin-1 protein forms a stack of four beta-hairpins, whereas its amino-terminal fragment appears to adopt a very stable stack of two beta-hairpins in solution. Here we determined a refined three-dimensional structure of this peptide fragment to examine potential conformational changes compared with the full-length protein. The structures were calculated with both a traditional method and a fast semiautomated method using ambiguous NMR distance restraints. The resulting sets of structures are very similar and show that a well-defined stack of two beta-hairpins is retained in the peptide. Conformational rearrangements compensating the loss of the carboxy-terminal subdomain of the native protein are restricted to the carboxy-terminal end of the peptide, the turn connecting the two beta-hairpins, and the Tyr(21) and Tyr(25) aromatic side chains. Further removal of the Val(1) and Ile(2) residues, which are part of the first beta-hairpin and components of two major hydrophobic clusters in the two beta-hairpin structure, results in the loss of the first beta-hairpin. The second beta-hairpin, which is closely associated with the first, retains a similar but somewhat less stable conformation. The invariable presence of the second beta-hairpin and the dependence of its stability on the first beta-hairpin suggest that the stack of two beta-hairpins may be an evolutionary conserved and autonomous folding unit. In addition, the high conformational stability makes the stack of two beta-hairpins an attractive scaffold for the development of peptide-based drug candidates.
authors.affiliation: Biomolecular NMR Laboratory and the Montreal Joint Centre for Structural Biology, Biotechnology Research Institute, National Research Council of Canada, Montreal, Quebec, Canada.
authors.forename: Wim F
authors.initials: WF
authors.lastname: Vranken
authors.forename: Susan
authors.initials: S
authors.lastname: James
authors.forename: Hugh P J
authors.initials: HP
authors.lastname: Bennett
authors.forename: Feng
authors.initials: F
authors.lastname: Ni
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002347:Carps; D000077155:Granulins; D036341:Intercellular Signaling Peptides and Proteins; D008956:Models, Chemical; D008958:Models, Molecular; D008969:Molecular Sequence Data; D019906:Nuclear Magnetic Resonance, Biomolecular; D009716:Numerical Analysis, Computer-Assisted; D010446:Peptide Fragments / Q000737:chemistry*; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D011506:Proteins / Q000737:chemistry*; D017384:Sequence Deletion
chemical_list: D000077155:Granulins; D036341:Intercellular Signaling Peptides and Proteins; D010446:Peptide Fragments; D011506:Proteins