RESUMO
Legume lectins are the most thoroughly studied group of lectins and have been widely linked to many pathological processes. Their use as immunohistochemistry markers for cell profiling and cancer diagnosis have made these molecules important tools for immunological studies and have stimulated the prospection and characterization of new lectins. The crystal structures of a recombinant seed lectin from Vatairea macrocarpa (rVML) and its complexes with GalNAcα1-O-Ser, GalNAc and α-lactose, have been determined at 1.90, 1.97, 2.70 and 1.83Å resolution, respectively. Small angle X-ray scattering and calorimetry assays have confirmed the same pH stable oligomerization pattern and binding profiles proposed for its wild-type counterpart. In silico analyzes have explored the potential of this recombinant lectin as new tool for cancer research through a comparative profile with other legume lectins widely used for cancer diagnosis and prognosis. The results suggest the recognition of specific epitopes exhibited on different cancer cells as a process that relies on the disposition of hydrophobic clusters and charged regions around the lectin carbohydrate-binding site, favouring the anchorage of different groups in the antigen boundaries, highlighting the different potential of each analyzed lectin. In conclusion, the experimental results and comparative analysis show that rVML is as a promising tool for cancer research, able to bind with high affinity specific tumor-associated antigens, highly stable and easily produced.
Assuntos
Antígenos Glicosídicos Associados a Tumores/metabolismo , Fabaceae/química , Neoplasias/metabolismo , Lectinas de Plantas/química , Lectinas de Plantas/metabolismo , Acetilgalactosamina/metabolismo , Lactose/metabolismo , Simulação de Acoplamento Molecular , Ligação Proteica , Conformação ProteicaRESUMO
Biofilms are assemblages of microorganisms and their associated extracellular products at an interface and typically with an abiotic or biotic surface. The study of the morphology of biofilms is important because they are associated with processes of biofouling, corrosion, catalysis, pollutant transformation, dental caries, drug resistance, and so forth. In the literature, biofilms have been examined by atomic force microscopy (AFM), which has proven to be a potent tool to study different aspects of the biofilm development on solid surfaces. In this work, we used AFM to investigate topographical changes during the development process of Enterococcus faecalis biofilms, which were generated on sterile cellulose nitrate membrane (CNM) filters in brain heart infusion (BHI) broth agar blood plates after 24, 36, 72, 192, and 360 h. AFM height images showed topographical changes due to biofilm development, which were used to characterize several aspects of the bacterial surface, such as the presence of extracellular polymeric substance, and the biofilm development stage. Changes in the development stage of the biofilm were shown to correlate with changes in the surface roughness as quantified through the mean roughness.
Assuntos
Biofilmes/crescimento & desenvolvimento , Colódio , Enterococcus faecalis/crescimento & desenvolvimento , Filtros Microporos , Microscopia de Força Atômica/métodos , Meios de Cultura , Humanos , Propriedades de SuperfícieRESUMO
BACKGROUND: Lectins are mainly described as simple carbohydrate-binding proteins. Previous studies have tried to identify other binding sites, which possible recognize plant hormones, secondary metabolites, and isolated amino acid residues. We report the crystal structure of a lectin isolated from Canavalia gladiata seeds (CGL), describing a new binding pocket, which may be related to pathogen resistance activity in ConA-like lectins; a site where a non-protein amino-acid, alpha-aminobutyric acid (Abu), is bound. RESULTS: The overall structure of native CGL and complexed with alpha-methyl-mannoside and Abu have been refined at 2.3 A and 2.31 A resolution, respectively. Analysis of the electron density maps of the CGL structure shows clearly the presence of Abu, which was confirmed by mass spectrometry. CONCLUSION: The presence of Abu in a plant lectin structure strongly indicates the ability of lectins on carrying secondary metabolites. Comparison of the amino acids composing the site with other legume lectins revealed that this site is conserved, providing an evidence of the biological relevance of this site. This new action of lectins strengthens their role in defense mechanisms in plants.
Assuntos
Canavalia/química , Lectinas de Plantas/química , Sementes/química , Aminobutiratos/química , Aminobutiratos/metabolismo , Sítios de Ligação , Cristalografia por Raios X , Interações Hidrofóbicas e Hidrofílicas , Modelos Moleculares , Lectinas de Plantas/metabolismo , Ligação Proteica , Conformação Proteica , Estrutura Terciária de Proteína , Espectrometria de Massas por Ionização por ElectrosprayRESUMO
A chitin-binding protein named PPL-2 was purified from Parkia platycephala seeds and crystallized. Crystals belong to the orthorhombic space group P2(1)2(1)2(1), with unit-cell parameters a = 55.19, b = 59.95, c = 76.60 A, and grew over several days at 293 K using the hanging-drop method. Using synchrotron radiation, a complete structural data set was collected to 1.73 A resolution. The preliminary crystal structure of PPL-2, determined by molecular replacement, presents a correlation coefficient of 0.558 and an R factor of 0.439. Crystallographic refinement is in progress.