Effects of turn residues in directing the formation of the β-sheet and in the stability of the β-sheet
Journal
Protein Science
Journal Volume
10
Journal Issue
9
Pages
1794-1800
Date Issued
2001
Author(s)
Abstract
The designed peptide (denoted 20-mer, sequence VFITSDPGKTYTEVDPGOKILQ) has been shown to form a three-strand antiparallel β-sheet. It is generally believed that the DPro-Gly segment has the propensity to adopt a type II′ β-turn, thereby promoting the formation of this β-sheet. Here, we replaced DPro-Gly with Asp-Gly, which should favor a type 1′ turn, to examine the influence of different type of turns on the stability of the β-sheet. Contrary to our expectation, the mutant peptide, denoted P6D, forms a five-residue type I turn plus a β-bulge between the first two strands due to a one amino-acid frameshift in the hydrogen bonding network and side-chain inversion of the first β-strand. In contrast, the same kind of substitution at DPro-14 in the double mutant, denoted P6DP14D, does not yield the same effect. These observations suggest that the SDGK sequence disfavors the type I′ conformation while the VDGO sequence favors a type I′ turn, and that the frameshift in the first strand provides a way for the peptide to accommodate a disfavored turn sequence by protruding a bulge in the formation of the β-hairpin. Thus, different types of turns can affect the stability of a β-structure.
Subjects
β-hairpin; β-sheet; NMR; Peptide; Protein folding; Site-directed mutagenesis; Stability; Structure; Turn
SDGs
Other Subjects
amino acid; hydrogen; peptide; protein; article; circular dichroism; hydrogen bond; nuclear magnetic resonance; nuclear Overhauser effect; priority journal; protein folding; protein stability; site directed mutagenesis; Amino Acid Sequence; Amino Acid Substitution; Circular Dichroism; Molecular Sequence Data; Nuclear Magnetic Resonance, Biomolecular; Peptides; Protein Structure, Secondary; Structure-Activity Relationship; Thermodynamics
Type
journal article