Crystal structures of the free and sterol-bound forms of beta-cinnamomin.

Maria Luisa Rodrigues, Margarida Archer, Paulo Martel, Sandra Miranda, Mónica Thomaz, Francisco Javier Enguita, Ricardo P Baptista, Eduardo Pinho e Melo, Nelson Sousa, Alfredo Cravador, Maria Arménia Carrondo

Journal: Biochimica et biophysica acta 2006;1764(1):110-21

PMID: 16249127

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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.

Address: Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, ITQB-UNL, Av. República, Apt. 127, 2781-901 Oeiras, Portugal.

DOI: 10.1016/j.bbapap.2005.09.008

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MeSH Terms: Algal Proteins, Binding Sites, Crystallization, Crystallography, X-Ray, Ergosterol, Genes, Ligands, Macromolecular Substances, Models, Molecular, Pentacyclic Triterpenes, Phytophthora, Protein Binding, Protein Conformation, Recombinant Proteins, Ribosome Inactivating Proteins, Type 2, Static Electricity, Sterols, Thermodynamics, Nicotiana, Triterpenes