Browsing by Author "Carrondo, Maria A."
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- Crystal structures of the free and sterol-bound forms of beta-cinnamominPublication . Rodrigues, Maria Luisa; Archer, Margarida; Martel, Paulo; Miranda, Sandra; Thomaz, Mónica; Enguita, Francisco J.; Baptista, Ricardo P.; Melo, Eduardo P.; Sousa, Nelson; Cravador, A.; Carrondo, Maria A.The crystal structure of the elicitin h-cinnamomin (h-CIN) was determined in complex with ergosterol at 1.1 A° resolution. h-CIN/ergosterol complex crystallized in the monoclinic space group P21, with unit cell parameters of a =31.0, b =62.8, c =50.0 A° and b =93.4- and two molecules in the asymmetric unit. Ligand extraction with chloroform followed by crystallographic analysis yielded a 1.35 A° structure of h-CIN (P43212 space group) where the characteristic elicitin fold was kept. After incubation with cholesterol, a new complex structure was obtained, showing that the protein retains, after the extraction procedure, its ability to complex sterols. The necrotic effect of h-CIN on tobacco was also shown to remain unchanged. Theoretical docking studies of the triterpene lupeol to h-CIN provided an explanation for the apparent inability of h-CIN to bind this ligand, as observed experimentally. D 2005 Elsevier B.V. All rights reserved.
- Crystallisation and preliminary X-ray diffraction analysis of alpha-cinnamomin, an elicitin secreted by the phytopathogenic fungus Phytophthora cinnamomiPublication . Archer, Margarida; Rodrigues, Maria Luisa; Aurélio, M.; Biemans, R.; Cravador, A.; Carrondo, Maria A.Cinnamomin (CIN) belongs to a family of 10 kDa proteins designated as elicitins. Some of these proteins induce a hypersensitive response in diverse plant species, leading to resistance against fungal and bacterial plant pathogens. CIN was crystallized by the vapourdiffusion method using either ammonium sulfate or polyethyleneglycol (PEG) as precipitants in solutions buffered at around pH 7. These crystals are isomorphous and belong to the triclinic space group, with unit-cell parameters a = 31.69, b = 36.99, c = 44.09 A Ê , = 76.86, = 84.41, = 80.26 . A frozen crystal diffracted X-rays beyond 1.45 A Ê resolution on a synchrotron-radiation source.
- Structure of beta-cinnamomin, a protein toxic to some plant speciesPublication . Rodrigues, M.; Archer, Margarida; Martel, P.; Jacquet, Alain; Cravador, A.; Carrondo, Maria A.Phytophthora and Pythium species are among the most aggressive plant pathogens, as they invade many economically important crops and forest trees. They secrete large amounts of 10 kDa proteins called elicitins that can act as elicitors of plant defence mechanisms. These proteins may also induce a hypersensitive response (HR) including plant cell necrosis, with different levels of toxicity depending on their pI. Recent studies showed that elicitins function as sterol carrier proteins. The crystallographic structure of the highly necrotic recombinant beta-cinnamomin (beta-CIN) from Phytophthora cinnamomi has been determined at 1.8 Angstrom resolution using the molecular-replacement method. beta-CIN has the same overall structure as beta-cryptogein (beta-CRY), an elicitin secreted by Phytophthora cryptogea, although it shows a different surface electrostatic potential distribution. The protein was expressed in Pichia pastoris and crystallized in the triclinic space group with two monomers in the asymmetric unit. The interface formed by these two monomers resembles that from beta-CRY dimer, although with fewer interactions.