title: Crystal structures of the free and sterol-bound forms of beta-cinnamomin.
abstract: The crystal structure of the elicitin beta-cinnamomin (beta-CIN) was determined in complex with ergosterol at 1.1 A resolution. beta-CIN/ergosterol complex crystallized in the monoclinic space group P2(1), with unit cell parameters of a = 31.0, b = 62.8, c = 50.0 A and beta = 93.4 degrees and two molecules in the asymmetric unit. Ligand extraction with chloroform followed by crystallographic analysis yielded a 1.35 A structure of beta-CIN (P4(3)2(1)2 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 beta-CIN on tobacco was also shown to remain unchanged. Theoretical docking studies of the triterpene lupeol to beta-CIN provided an explanation for the apparent inability of beta-CIN to bind this ligand, as observed experimentally.
authors.affiliation: Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, ITQB-UNL, Av. República, Apt. 127, 2781-901 Oeiras, Portugal.
authors.forename: Maria Luisa
authors.initials: ML
authors.lastname: Rodrigues
authors.forename: Margarida
authors.initials: M
authors.lastname: Archer
authors.forename: Paulo
authors.initials: P
authors.lastname: Martel
authors.forename: Sandra
authors.initials: S
authors.lastname: Miranda
authors.forename: Mónica
authors.initials: M
authors.lastname: Thomaz
authors.forename: Francisco Javier
authors.initials: FJ
authors.lastname: Enguita
authors.forename: Ricardo P
authors.initials: RP
authors.lastname: Baptista
authors.forename: Eduardo
authors.initials: E
authors.lastname: Pinho e Melo
authors.forename: Nelson
authors.initials: N
authors.lastname: Sousa
authors.forename: Alfredo
authors.initials: A
authors.lastname: Cravador
authors.forename: Maria Arménia
authors.initials: MA
authors.lastname: Carrondo
mesh_terms: D020418:Algal Proteins / Q000737:chemistry* / Q000235:genetics / Q000633:toxicity; D001665:Binding Sites; D003460:Crystallization; D018360:Crystallography, X-Ray; D004875:Ergosterol / Q000737:chemistry; D005796:Genes; D008024:Ligands; D046911:Macromolecular Substances; D008958:Models, Molecular; D053978:Pentacyclic Triterpenes; D010838:Phytophthora / Q000737:chemistry / Q000235:genetics / Q000472:pathogenicity; D011485:Protein Binding; D011487:Protein Conformation; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000633:toxicity; D054790:Ribosome Inactivating Proteins, Type 2; D055672:Static Electricity; D013261:Sterols / Q000737:chemistry; D013816:Thermodynamics; D014026:Nicotiana / Q000187:drug effects; D014315:Triterpenes / Q000737:chemistry; D000094042:Lupanes
chemical_list: D020418:Algal Proteins; D004875:Ergosterol; D008024:Ligands; D046911:Macromolecular Substances; D053978:Pentacyclic Triterpenes; D011994:Recombinant Proteins; D054790:Ribosome Inactivating Proteins, Type 2; D013261:Sterols; D014315:Triterpenes; C061930:cinnamomin, Phytophthora cinnamomi; C010480:lupeol; D000094042:Lupanes