Morintides: cargo-free chitin-binding peptides from Moringa oleifera

Statistics of the structure of mO1 generated by CNSsolve 1.3. (DOCX 16 kb

Studies on the Chitin Binding Property of Novel Cysteine-Rich Peptides from Alternanthera sessilis

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.NRF (Natl Research Foundation, S’pore)Accepted versio

Vaccatides: Antifungal Glutamine-Rich Hevein-Like Peptides from Vaccaria hispanica

Hevein and hevein-like peptides are disulfide-constrained chitin-binding cysteine-rich peptides. They are divided into three subfamilies, 6C-, 8C-, and 10C-hevein-like peptides, based on the number of cysteine residues. In addition, hevein-like peptides can exist in two forms, short and long. The long C-terminal form found in hevein and 10C-hevein-like peptides contain a C-terminal protein cargo. In contrast, the short form without a protein cargo is found in all three subfamilies. Here, we report the discovery and characterization of two novel glutamine-rich and protein cargo-free 8C-hevein-like peptides, vaccatides vH1 and vH2, from Vaccaria hispanica of the Caryophyllaceae family. Proteomic analyses showed that the vaccatides are 40–41 amino acids in length and contain a chitin-binding domain. NMR determination revealed that vaccatide vH2 displays a highly compact structure with a N-terminal cystine knot and an addition C-terminal disulfide bond. Stability studies showed that this compact structure renders vaccatide vH2 resistant to thermal, chemical and proteolytic degradation. The chitin-binding vH2 was shown to inhibit the mycelium growth of four phyto-pathogenic fungal strains with IC50 values in the micromolar range. Our findings show that vaccatides represent a new family of 8C-hevein-like peptides, which are protein cargo-free and glutamine-rich, characteristics that differentiate them from the prototypic hevein and the 10C-hevein-like peptides. In summary, this study enriches the existing library of hevein-like peptides and provides insight into their molecular diversity in sequence, structure and biosynthesis. Additionally, their highly disulfide-constrained structure could be used as a scaffold for developing metabolically and orally active peptidyl therapeutics

Studies on the Chitin Binding Property of Novel Cysteine-Rich Peptides from <i>Alternanthera sessilis</i>

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 <i>Alternanthera sessilis</i>, 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. ¹H 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