title: A leucine-rich repeat peptide derived from the Drosophila Toll receptor forms extended filaments with a beta-sheet structure.
abstract: Leucine-rich repeats (LRRs) are 22-28 amino acid-long sequence motifs found in a family of cytoplasmic, membrane and extracellular proteins. There is evidence that LRRs function in signal transduction, cellular adhesion and protein-protein interactions. Here we report unusual properties of a synthetic LRR peptide derived from the sequence of the Drosophila membrane receptor Toll. In neutral solution the peptide forms a gel revealed by electron microscopy to consist of extended filaments approximately 8 nm in thickness. As the gel forms, the circular dichroism spectrum of the peptide solution changes from one characteristic of random coil to one associated with beta-sheet structures. Molecular modelling suggests that the peptide form an amphipathic structure with a predominantly apolar and charged surface. Based on these results, models for the gross structure of the peptides filaments and a possible molecular mechanism for cellular adhesion are proposed.
authors.affiliation: Department of Biochemistry, University of Cambridge, UK.
authors.forename: N J
authors.initials: NJ
authors.lastname: Gay
authors.forename: L C
authors.initials: LC
authors.lastname: Packman
authors.forename: M A
authors.initials: MA
authors.lastname: Weldon
authors.forename: J C
authors.initials: JC
authors.lastname: Barna
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002448:Cell Adhesion; D002851:Chromatography, High Pressure Liquid; D002942:Circular Dichroism; D004330:Drosophila / Q000737:chemistry* / Q000235:genetics; D029721:Drosophila Proteins; D007301:Insect Hormones / Q000737:chemistry* / Q000235:genetics; D007700:Kinetics; D007930:Leucine / Q000737:chemistry*; D000090263:Leucine-Rich Repeat Proteins; D008562:Membrane Glycoproteins / Q000737:chemistry* / Q000235:genetics; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011485:Protein Binding; D011487:Protein Conformation; D011506:Proteins / Q000737:chemistry* / Q000235:genetics; D011956:Receptors, Cell Surface / Q000737:chemistry* / Q000235:genetics; D012996:Solutions; D051193:Toll-Like Receptors
chemical_list: D029721:Drosophila Proteins; D007301:Insect Hormones; D000090263:Leucine-Rich Repeat Proteins; D008562:Membrane Glycoproteins; D011506:Proteins; D011956:Receptors, Cell Surface; D012996:Solutions; C068721:Tl protein, Drosophila; D051193:Toll-Like Receptors; D007930:Leucine