title: Osmotin from Calotropis procera latex: new insights into structure and antifungal properties.
abstract: This study aimed at investigating the structural properties and mechanisms of the antifungal action of CpOsm, a purified osmotin from Calotropis procera latex. Fluorescence and CD assays revealed that the CpOsm structure is highly stable, regardless of pH levels. Accordingly, CpOsm inhibited the spore germination of Fusarium solani in all pH ranges tested. The content of the secondary structure of CpOsm was estimated as follows: α-helix (20%), β-sheet (33%), turned (19%) and unordered (28%), RMSD 1%. CpOsm was stable at up to 75°C, and thermal denaturation (T(m)) was calculated to be 77.8°C. This osmotin interacted with the negatively charged large unilamellar vesicles (LUVs) of 1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-rac-1-glycerol (POPG), inducing vesicle permeabilization by the leakage of calcein. CpOsm induced the membrane permeabilization of spores and hyphae from Fusarium solani, allowing for propidium iodide uptake. These results show that CpOsm is a stable protein, and its antifungal activity involves membrane permeabilization, as property reported earlier for other osmotins and thaumatin-like proteins.
authors.affiliation: Departamento de Biologia, Universidade Federal do Piauí, Bairro Melladão, Floriano-Piauí, Brazil. cleversondiniz@hotmail.com
authors.forename: Cleverson Diniz Teixeira
authors.initials: CD
authors.lastname: de Freitas
authors.forename: José Luiz de Souza
authors.initials: JL
authors.lastname: Lopes
authors.forename: Leila Maria
authors.initials: LM
authors.lastname: Beltramini
authors.forename: Raquel Sombra Basílio
authors.initials: RS
authors.lastname: de Oliveira
authors.forename: José Tadeu Abreu
authors.initials: JT
authors.lastname: Oliveira
authors.forename: Márcio Viana
authors.initials: MV
authors.lastname: Ramos
mesh_terms: D000935:Antifungal Agents / Q000737:chemistry* / Q000494:pharmacology*; D031107:Calotropis / Q000737:chemistry*; D002852:Chromatography, Ion Exchange; D002942:Circular Dichroism; D006863:Hydrogen-Ion Concentration; D007840:Latex / Q000737:chemistry*; D015394:Molecular Structure; D010940:Plant Proteins / Q000737:chemistry* / Q000494:pharmacology*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013056:Spectrophotometry, Ultraviolet; D013329:Structure-Activity Relationship
chemical_list: D000935:Antifungal Agents; D007840:Latex; D010940:Plant Proteins