NMR structure and conformational dynamics of AtPDFL2.1, a defensin-like peptide from Arabidopsis thaliana

作者：Omidvar Reza; Xia Youlin; Porcelli Fernando; Bohlmann Holger; Veglia Gianluigi^*

来源：Biochimica et Biophysica Acta-Proteins and Proteomics, 2016, 1864(12): 1739-1747.

DOI：10.1016/j.bbapap.2016.08.017

• AtPDFL2.1
• Plant defensins
• Solution NMR
• Antifungal activity
• Three-dimensional structure
• Conformational dynamics

Plant defensins constitute the innate immune response against pathogens such as fungi and bacteria. Typical plant defensins are small, basic peptides that possess a characteristic three-dimensional fold stabilized by three or four disulfide bridges. In addition to known defensin genes, the Arabidopsis genome comprises >300 defensin-like genes coding for small cysteine-rich peptides. One of such genes encodes for AtPDFL2.1, a putative antifungal peptide of 55 amino acids, with six cysteine residues in its primary sequence. To understand the functional role of AtPDFL2.1, we carried out antifungal activity assays and determined its high-resolution three-dimensional structure using multidimensional solution NMR spectroscopy. We found that AtPDFL2.1 displays a strong inhibitory effect against Fusarium graminearum (IC50 approximate to 4 mu M). This peptide folds in the canonical cysteine-stabilized alpha beta (CS alpha beta) motif, consisting of one alpha-helix and one triple-stranded antiparallel beta-sheet stabilized by three disulfide bridges and a hydrophobic cluster of residues within its core where the alpha-helix packs tightly against the beta-sheets. Nuclear spin relaxation measurements show that the structure of AtPDFL2.1 is essentially rigid, with the L3 loop located between beta-strands 2 and 3 being more flexible and displaying conformational exchange. Interestingly, the dynamic features of loop 13 are conserved among defensins and are probably correlated to the antifungal and receptor binding activities.

• 出版日期2016-12