title: Structures of wild-type and mutant signal sequences of Escherichia coli ribose binding protein.
abstract: The structure of a chemically synthesized 25-residue-long functional signal peptide of Escherichia coli ribose binding protein was compared with that of a nonfunctional mutant-signal peptide using circular dichroism and two-dimensional 1H NMR in solvents mimicking the amphiphilic environments. The functional peptide forms an 18-residue-long alpha-helix starting from the NH2-terminal region and reaching to the hydrophobic stretch in a solvent consisting of 10% dimethylsulfoxide, 40% water, and 50% trifluoroethanol (v/v). The nonfunctional mutant peptide, which contains a Pro at position 9 instead of a Leu in the wild-type peptide, does not have any secondary structure in that solvent but forms a 12-residue-long alpha-helix within the hydrophobic stretch in water/trifluoroethanol (50:50, v/v) solvent. It seems that the Pro-9 residue in the nonfunctional peptide disturbs the helix propagation from the hydrophobic stretch to the NH2-terminal region. Because both of these peptides have stable helices within the hydrophobic stretch, it may be concluded that the additional 2 turns of the alpha-helix in the NH2-terminal region of the wild-type signal peptide is important for its function.
authors.affiliation: Department of Life Science, Korea Advanced Institute of Science and Technology, Taejon.
authors.forename: G S
authors.initials: GS
authors.lastname: Yi
authors.forename: B S
authors.initials: BS
authors.lastname: Choi
authors.forename: H
authors.initials: H
authors.lastname: Kim
mesh_terms: D000595:Amino Acid Sequence; D002352:Carrier Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D002942:Circular Dichroism; D004926:Escherichia coli / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D029968:Escherichia coli Proteins; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D015394:Molecular Structure; D009154:Mutation; D033902:Periplasmic Binding Proteins; D021382:Protein Sorting Signals / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D012266:Ribose / Q000378:metabolism
chemical_list: D002352:Carrier Proteins; D029968:Escherichia coli Proteins; D033902:Periplasmic Binding Proteins; D021382:Protein Sorting Signals; C028003:RbsB protein, E coli; D012266:Ribose