Identification of MpPR1-I protein ligands and structural and functional analyses of MpPR-1s of Moniliophthora perniciosa in vitro

Abstract

One of the best-studied gene families related to plant defense mechanisms encode proteins known as PR-1 (pathogenesis related protein 1). These proteins play an important role during pathogen-host interactions, can block the development of fungi and act as systemic acquired resistance marker. Interestingly, protein members of this superfamily SCP/TAPS that expressed by pathogenic nematodes, both from animals and plants, have immunomodulatory effects and suppress the host's defense response. Recently, it was found that proteins belonging to the SCP/TAPS superfamily, which includes PR-1 proteins, are capable of transporting cholesterol and bind to fatty acids and steroid molecules. Furthermore, it was shown that SCP/TAPS proteins have the ability to inhibit the action of hydrophobic plant-derived antifungal molecules. Notably, previous results from our group indicate that the protein MpPR-1k from Moniliophthora perniciosa would have the ability to export cholesterol and selectively bind to cholesterol, and MpPR-1i, binding palmitate.Thus, this project seeks to expand the understanding the mechanism action of these two proteins regarding their ability to interact with hydrophobic molecules such as sterols and fatty acids, as well as to elucidate the relevance of this ability during plant-pathogen interaction. So, the following activities will be performed: 1) quantification of the level of gene expression of the different MpPR-1s in the presence of steroidal antifungal agents such as eugenol and alpha-tomatine; 2) identification of a lipid molecule that was detected as bound to MpPR1-i protein; 3) characterization of the interaction of MpPR-1i with binders by co-crystallization assays followed by structural resolution by X-ray diffraction; 4) structural resolution of a mutant version of MpPR-1i that has acquired the ability to bind to cholesterol and o fMpPR-1ik that was found to bind to cholesterol. Therefore, we intend to understand more closely the mechanisms of action of these proteins in the plant-pathogen interaction, and especially during the interaction of M. perniciosa -cacao.