title: Camptosemin, a tetrameric lectin of Camptosema ellipticum: structural and functional analysis.
abstract: Lectins have been classified into a structurally diverse group of proteins that bind carbohydrates and glycoconjugates with high specificity. They are extremely useful molecules in the characterization of saccharides, as drug delivery mediators, and even as cellular surface makers. In this study, we present camptosemin, a new lectin from Camptosema ellipticum. It was characterized as an N-acetyl-D-galactosamine-binding homo-tetrameric lectin, with a molecular weight around 26 kDa/monomers. The monomers were stable over a wide range of pH values and exhibited pH-dependent oligomerization. Camptosemin promoted adhesion of breast cancer cells and hemagglutination, and both activities were inhibited by its binding of sugar. The stability and unfolding/folding behavior of this lectin was characterized using fluorescence and far-UV circular dichroism spectroscopies. The results indicate that chemical unfolding of camptosemin proceeds as a two-state monomer-tetramer process. In addition, small-angle X-ray scattering shows that camptosemin behaves as a soluble and stable homo-tetramer molecule in solution.
authors.affiliation: Centro de Biotecnologia Molecular Estrutural (CBME), Instituto de Física de São Carlos (IFSC), Universidade de São Paulo (USP), São Carlos, Brazil.
authors.forename: Fernanda A H
authors.initials: FA
authors.lastname: Batista
authors.forename: Leandro S
authors.initials: LS
authors.lastname: Goto
authors.forename: Wanius
authors.initials: W
authors.lastname: Garcia
authors.forename: Derminda I
authors.initials: DI
authors.lastname: de Moraes
authors.forename: Mario
authors.initials: M
authors.lastname: de Oliveira Neto
authors.forename: Igor
authors.initials: I
authors.lastname: Polikarpov
authors.forename: Marcia R
authors.initials: MR
authors.lastname: Cominetti
authors.forename: Heloísa S
authors.initials: HS
authors.lastname: Selistre-de-Araújo
authors.forename: Leila M
authors.initials: LM
authors.lastname: Beltramini
authors.forename: Ana Paula Ulian
authors.initials: AP
authors.lastname: Araújo
mesh_terms: D000116:Acetylgalactosamine / Q000737:chemistry; D001943:Breast Neoplasms / Q000737:chemistry; D002241:Carbohydrates / Q000737:chemistry; D002448:Cell Adhesion; D045744:Cell Line, Tumor; D002942:Circular Dichroism; D007887:Fabaceae / Q000737:chemistry*; D005260:Female; D029624:Ferns; D006384:Hemagglutination; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008970:Molecular Weight; D037121:Plant Lectins / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification; D011485:Protein Binding; D011487:Protein Conformation; D055503:Protein Multimerization; D055550:Protein Stability; D053838:Scattering, Small Angle; D017386:Sequence Homology, Amino Acid; D013050:Spectrometry, Fluorescence; D014466:Ultraviolet Rays; D014961:X-Ray Diffraction
chemical_list: D002241:Carbohydrates; D037121:Plant Lectins; D000116:Acetylgalactosamine