title: Studies on the Chitin Binding Property of Novel Cysteine-Rich Peptides from Alternanthera sessilis.
abstract: Hevein-like peptides make up a family of cysteine-rich peptides (CRPs) and play a role in plants in their defense against insects and fungal pathogens. In this study, we report the isolation and characterization of six hevein-like peptides, aSG1-G3 and aSR1-R3, collectively named altides from green and red varieties of Alternanthera sessilis, a perennial herb belonging to the Amaranthaceae family. Proteomic analysis of altides revealed they contain six cysteines (6C), seven glycines, four prolines, and a conserved chitin-binding domain (SXYGY/SXFGY). Thus far, only four 6C-hevein-like peptides have been isolated and characterized; hence, our study expands the existing library of these peptides. Nuclear magnetic resonance (NMR) study of altides showed its three disulfide bonds were arranged in a cystine knot motif. As a consequence of this disulfide arrangement, they are stable against thermal and enzymatic degradation. Gene cloning studies revealed altides contain a three-domain precursor with an endoplasmic reticulum signal peptide followed by a mature CRP domain and a short C-terminal tail. This indicates that the biosynthesis of altides is through the secretory pathway. (1)H NMR titration experiments showed that the 29-30-amino acid altides bind to chitin oligomers with dissociation constants in the micromolar range. Aromatic residues in the chitin-binding domain of altides were involved in the binding interaction. To the best of our knowledge, aSR1 is the smallest hevein-like peptide with a dissociation constant toward chitotriose comparable to those of hevein and other hevein-like peptides. Together, our study expands the existing library of 6C-hevein-like peptides and provides insights into their structure, biosynthesis, and interaction with chitin oligosaccharides.
authors.affiliation: School of Biological Sciences, Nanyang Technological University , Singapore 637551.
authors.forename: Shruthi G
authors.initials: SG
authors.lastname: Kini
authors.affiliation: School of Biological Sciences, Nanyang Technological University , Singapore 637551.
authors.forename: Phuong Q T
authors.initials: PQ
authors.lastname: Nguyen
authors.affiliation: Institut für Chemie, Universität zu Lübeck , Lübeck, Germany.
authors.forename: Sophie
authors.initials: S
authors.lastname: Weissbach
authors.affiliation: Institut für Chemie, Universität zu Lübeck , Lübeck, Germany.
authors.forename: Alvaro
authors.initials: A
authors.lastname: Mallagaray
authors.affiliation: School of Biological Sciences, Nanyang Technological University , Singapore 637551.
authors.forename: Joon
authors.initials: J
authors.lastname: Shin
authors.affiliation: School of Biological Sciences, Nanyang Technological University , Singapore 637551.
authors.forename: Ho Sup
authors.initials: HS
authors.lastname: Yoon
authors.affiliation: School of Biological Sciences, Nanyang Technological University , Singapore 637551.
authors.forename: James P
authors.initials: JP
authors.lastname: Tam
mesh_terms: D027703:Amaranthaceae / Q000235:genetics / Q000378:metabolism*; D000595:Amino Acid Sequence; D023181:Antimicrobial Cationic Peptides / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D001665:Binding Sites / Q000235:genetics; D002686:Chitin / Q000378:metabolism*; D003545:Cysteine / Q000737:chemistry; D017343:Genes, Plant; D008958:Models, Molecular; D008969:Molecular Sequence Data; D019906:Nuclear Magnetic Resonance, Biomolecular; D010455:Peptides / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D010940:Plant Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D055550:Protein Stability; D017386:Sequence Homology, Amino Acid; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D023181:Antimicrobial Cationic Peptides; D010455:Peptides; D010940:Plant Proteins; D002686:Chitin; D003545:Cysteine