NMR structure, conformational dynamics, and biological activity of PsDef1 defensin from Pinus sylvestris

- Solution NMR structure of Scotts pine defensin PsDef1 shows a canonical CSαβ fold.
- PsDef1 samples alternative folded conformational states.
- Temperature coefficients of PsDef1 reveal an unusual behavior of H37.
- PsDef1 inhibits growth of Gram-positive and Gram-negative bacteria.
- PsDef1 inhibits P. flammea α-amylase activity.

Plants have developed a complex defense response system against pests and pathogens. Defensins, produced by plants as part of their innate immune response, form the family of small, basic, cysteine-rich proteins with activity primarily directed against fungal pathogens. In addition, plant defensins can show antibacterial activity and protease and insect amylase inhibitory activities. However, in gymnosperms, only antifungal activity of defensins has been described thus far. Here, we report antibacterial and insect α-amylase inhibition activities for defensin PsDef1 from P. sylvestris, the first defensin from gymnosperms with a broad range of biological activities described. We also report the solution NMR structure of PsDef1 and its dynamics properties assessed by a combination of experimental NMR and computational techniques. Collectively, our data provide an insight into structure, dynamics, and functional properties of PsDef1 that could be common between defensins from this taxonomic group.