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Crystal structures of the free and sterol-bound forms of β-cinnamomin

2005; Elsevier BV; Volume: 1764; Issue: 1 Linguagem: Inglês

10.1016/j.bbapap.2005.09.008

1878-1454

Maria Luı́sa Rodrigues, Margarida Archer, Paulo Martel, S. Miranda, M. Thomaz, Francisco J. Enguita, Ricardo P. Baptista, Eduardo P. Melo, Nelson Sousa, Alfredo Cravador, M.A. Carrondo,

Genomics, phytochemicals, and oxidative stress

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.