Discovery and characterization of Hevein-like peptides from Avena sativa

• Main Author: Tan, Adeline Jia Ler
• Other Authors: Jimmy Pingkwan Tam @ James P Tam
• Format: Final Year Project
• Language: English
• Published: 2017
• Subjects: DRNTU::Science
• Online Access: http://hdl.handle.net/10356/72500
• Institution: Nanyang Technological University

Hevein and hevein-like peptides belong to the family of cysteine-rich peptides (CRPs) with a distinctive chitin-binding domain. They are classified, based on the number of cysteine residues, into three subfamilies namely the prototypic 8C- and the 6C- and 10C-hevein-like peptides. Here, we report the discovery and characterization of 9 novel 8C-hevein-like peptides, designated avenatides aV1–aV9 from seeds of Avena sativa. Reduction and alkylation tests determined the presence of 4 disulfide bonds formed from 8 cysteine residues. Stability studies on heat, acid and enzymatic degradation displayed avenatide’s high threshold to extreme conditions. Proteomic analysis determined that avenatides were 39 amino acids long in sequence and had a conserved chitin-binding motif thus confirmed their place in 8C-HLP family. Chitin-binding assay further confirmed the presence of chitin-binding activity. Anti-fungal assays such as disc diffusion and microbroth dilution assays revealed avenatide’s ability to inhibit mycelium growth of phyto-pathogenic fungi. Transcriptomic analysis revealed the presence of a signal sequence, 4 tandem repeats of hevein-like peptide domain, 3 hinge domain and a C-terminal tail, contributed to the four-domain architecture in avenatide precursors. Our findings serves to enhance the current archive of hevein-like peptides and offer understanding of their molecular diversity in sequence, structure and biosynthesis.