The crystal structure of Canavalia brasiliensis lectin suggests a correlation between its quaternary conformation and its distinct biological properties from Concanavalin A

5 pags, 2 figs, 1 tabsCanavalia brasiliensis lectin was isolated from the seeds of a Brazilian autochthonous Leguminosae plant. Despite extensive amino acid sequence similarity with Concanavalin A, C. brasiliensis lectin exerts in vitro and in vivo cellular effects that are markedly different from those displayed by Concanavalin A. We have solved the crystal structure of the C. brasiliensis lectin at 3.0 Å resolution. The three-dimensional structure of the lectin monomer can be superimposed onto that of Concanavalin A with a root-mean-square deviation for all Cα atoms of 0.65 Å. However, this parameter is 0.84 and 1.62 Å when the C. brasiliensis lectin dimer and tetramer, respectively, are compared with the same structures of Concanavalin A. We suggest that these differences in quaternary structure may account for the different biological properties of these two highly related Leguminosae lectins.This work was supported by grants from Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), Financiadora de Estudos e Projetos (FINEP), Coordenaçâo de Aperfeiçoamento de Pessoal de Nivel Superior (CAPES), International Foundation for Science (IFS), Programa de Apoio ao Desenvolvimento Científico e Tecnológico (PADCT), and Fundaçâo Cearense de Amparo à Pesquisa (FUNCAPE), Brasil, and grant PB95-0077 from Dirección General de Investigaciones Científicas y Técnicas, Madrid, Spain