Unfoldome variation upon plant-pathogen interactions: strawberry infection by Colletotrichum acutatum

Abstract

Intrinsically disordered proteins (IDPs) are proteins that lack secondary and/or tertiary structure under physiological conditions. These proteins are very abundant in eukaryotic proteomes and play crucial roles in all molecular mechanisms underlying the response to environmental challenges. In plants, different IDPs involved in stress response have been identified and characterized. Nevertheless, a comprehensive evaluation of protein disorder in plant proteomes under abiotic or biotic stresses is not available so far. In the present work the transcriptome dataset of strawberry (Fragaria X ananassa) fruits interacting with the fungal pathogen Colletotrichum acutatum was actualized onto the woodland strawberry (Fragaria vesca) genome. The obtained cDNA sequences were translated into protein sequences, which were subsequently subjected to disorder analysis. The results, providing the first estimation of disorder abundance associated to plant infection, showed that the proteome activated in the strawberry red fruit during the active fungal propagation is remarkably depleted in disorder. On the other hand, in the resistant white fruit, no significant disorder reduction is observed in the proteins expressed in response to fungal infection. Four representative proteins, FvSMP, FvPRKRIP, FvPCD-4 and FvFAM32A-like, predicted as mainly disordered and never experimentally characterized before, were isolated, and the absence of structure was validated at the secondary and tertiary level using circular dichroism and differential scanning fluorimetry. Their quaternary structure was also established using light scattering. The results are discussed considering the role of protein disorder in plant defense.

Structural analysis of the interaction between Jaburetox, an intrinsically disordered protein, and membrane models

“…Circular dichroism spectra of 25 M Jbtx solutions in 50 mM NaPB at pH 6.5 were recorded in 0.1 cm path length cuvettes at 25 • C using a Jasco 810 spectropolarimeter (Jasco Inc., Easton, MD, USA) in the 190 − 260 nm range, as a function of different amounts of SDS micelles, LUVs or lipid bicelles. The fraction of ␣-helices of the protein was calculated from mean residue ellipticity at 222 nm as previously reported [36,37]. Care was taken to obtain signals below the maximum value of the high-tension (HT) voltage, as provided by the spectropolarimeter manufacturer (700 V).…”