In silico identification of non-chitin binding hevein-like peptides in planta

• Main Author: Kee, Vivian Jie Yi
• Other Authors: James P. Tam
• Format: Final Year Project
• Language: English
• Published: 2019
• Subjects: Science::Biological sciences
• Online Access: http://hdl.handle.net/10356/78855
• Institution: Nanyang Technological University

Cysteine-rich peptides (CRPs) are naturally occurring in animals, insects, and plants. They are mini-proteins with molecular weights of 2 to 6 kDa and contains a primary sequence with six to 10 cysteine residues. The cysteine residues form disulfide linkages and provide a highly resistant structure against heat, acid and enzymatic degradation. Reports on the classification of CRPs show that defensins are the largest CRP family. Our laboratory however, discovered that hevein-like peptides (HLPs) are as or even more abundant than defensins. Thus, there is a need to revise the current classification system for CRPs. HLPs are known for its chitin-binding and antifungal activities. In this study, we report a new class of HLPs which has the same cysteine motif and disulfide connectivity as the existing HLPs but do not have chitin-binding domain or activities. Using in silico methods, data mining was performed using the cysteine motifs of 6 Cysteine- (6C-) non-chitin binding (NCB) HLPs and 8 Cysteine- (8C-) NCB HLPs as query sequences. Our results revealed the identification of 117 unique 6C- and 8C-NCB HLPs. Sequence and biosynthetic analysis revealed the absolute conservation of their HLP cysteine motifs. Structural modelling showed the similar conformational fold for all the identified NCB HLPs. Prediction of ligand binding activities using I-TASSER revealed the variety of potential activities each of the NCB HLPs might possess. Further studies are required for the physical and functional characterization of the identified candidates. Together, this study expands the existing HLP family through the sub classification of chitin-binding and NCB HLPs. More importantly, provided new insights into the molecular diversity of plant CRPs and showcases their potential functional variety.