Genotypes of the mannan-binding lectin gene and susceptibility to visceral leishmaniasis and clinical complications

Background. Visceral leishmaniasis (VL) is almost always lethal if not treated, but most infections with the causative agents are clinically silent. Mannan-binding lectin (MBL), an opsonin, is a candidate molecule for modifying progression to VL because it may enhance infection with intracellular pathogens. Mutations in the MBL2 gene decrease levels of MBL and may protect against development of VL. This case-control study examines genotypes of MBL2 and levels of MBL in individuals presenting with different outcomes of infection with Leishmania chagasi.Methods. Genotypes for MBL2 and levels of serum MBL were determined in uninfected control subjects (n=76) and in individuals presenting with asymptomatic infection (n=90) or VL (n=69).Results. Genotypes resulting in high levels of MBL were more frequent (odds ratio [OR], 2.5 [95% confidence interval {CI}, 1.3-5.0]; P=.006) among individuals with VL than among those with asymptomatic infections and were even more frequent (OR, 3.97 [95% CI, 1.10-14.38];P=.043) among cases of VL presenting with clinical complications than among those with uneventful courses. Serum levels of MBL were higher (P=.011) in individuals with VL than in asymptomatic infections.Conclusions. Genotypes of the MBL2 gene predict the risk for developing VL and clinical complications in infections with L. chagasi.

Mannose-binding lectin gene polymorphism and risk factors for cardiovascular disease in postmenopausal women

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Jacalin interaction with human immunoglobulin A1 and bovine immunoglobulin G1: Affinity constant determined by piezoelectric biosensoring

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Real-time monitoring and kinetic parameter estimation of the affinity interaction of jArtinM and rArtinM with peroxidase glycoprotein by the electrogravimetric technique

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Identificação e análise de polimorfismos no gene que codifica a Lectina ligante de Manose (MBL) na espécie Canis lúpus familiaris

Pós-graduação em Biologia Geral e Aplicada - IBB

Pesquisa de mutação do gene predito da lectina ligante de manose em cães: comparação entre dois alvos para diagnóstico molecular de leishmaniose visceral canina

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Determinação da constante de afinidade e cinética da interação lectina ArtinM-célula leucêmica (NB4) por meio de técnicas piezoelétrica e eletroquímica

Pós-graduação em Biotecnologia - IQ

Genotipagem das mutações do gene humano que codifica a lectina ligante da manose de voluntários do Departamento de Parasitologia do Instituto de Biociências

A leishmaniose é uma doença causada pelo protozoário do gênero Leishmania, possuindo uma variedade de formas clínicas. A mais severa é a Leishmaniose visceral, que no Brasil é causada por L. chagasi e transmitida pelo flebotomíneo Lutzomia longipalpis. O cão, tanto o doméstico como o selvagem, é o principal reservatório no ciclo zoonótico da doença, que no Brasil ocorre principalmente na região nordeste. Através de estudos epidemiológicos realizados em áreas endêmicas, notou-se que apesar do elevado número de pessoas infectadas, poucas manifestavam a doença. Isso pode ser explicado pelo estado nutricional e imunológico do paciente, infecção por HIV e variabilidade das cepas, visto que a heterogeneidade genética e diversidade clonal estão relacionadas a variações nos fatores de virulência do parasita. A lectina que se liga à manose (Mannose-Binding Lectin), ou MBL, é uma proteína que pode estar relacionada ao desenvolvimento da doença, uma vez que pode se ligar a carboidratos na membrana externa de patógenos, agindo como uma opsonina e facilitando assim a ação de macrófagos. Altas concentrações desta proteína podem ser desvantajosas, uma vez que pode facilitar a infecção por LV. Genes mutados podem contribuir para a variação do nível sérico da proteína diminuindo as taxas de transcrição do gene. Concluindo, o projeto tem o intuito de identificar e genotipar mutações específicas no promotor e no exon 1 do gene que codifica a MBL em humanos. A realização do estudo permitirá também, a consolidação de uma base de dados para estudos posteriores envolvendo a genética populacional da Lectina Ligante de Manose

Quartz Crystal Microbalance monitoring the real-time binding of lectin with carbohydrate with high and low molecular mass

Quartz Crystal Microbalance (QCM) was used to monitor the mass changes on a quartz crystal surface containing immobilized lectins that interacted with carbohydrates. The strategy for lectin immobilization was developed on the basis of a multilayer system composed of Au-cystamine-glutaraldehyde-lectin. Each step of the immobilization procedure was confirmed by FTIR analysis. The system was used to study the interactions of Concanavalin A (ConA) with maltose and Jacalin with Fetuin. The real-time binding of different concentrations of carbohydrate to the immobilized lectin was monitored by means of QCM measurements and the data obtained allowed for the construction of Langmuir isotherm curves. The association constants determined for the specific interactions analyzed here were (6.4 +/- 0.2) X 10(4) M-1 for Jacalin-Fetuin and (4.5 +/- 0.1) x 10(2) M-1 for ConA-maltose. These results indicate that the QCM constitutes a suitable method for the analysis of lectin-carbohydrate interactions, even when assaying low molecular mass ligands such as disaccharides. Published by Elsevier B.V.

Impedance-derived electrochemical capacitance spectroscopy for the evaluation of lectin-glycoprotein binding affinity

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Structure of a lectin from Canavalia gladiata seeds: new structural insights for old molecules

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, aaminobutyric 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 angstrom and 2.31 angstrom 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.

cDNA cloning and 1.75 angstrom crystal structure determination of PPL2, an endochitinase and N-acetylglucosamine-binding hemagglutinin from Parkia platycephala seeds

Parkia platycephala lectin 2 was purified from Parkia platycephala (Leguminosae, Mimosoideae) seeds by affinity chromatography and RP-HPLC. Equilibrium sedimentation and MS showed that Parkia platycephala lectin 2 is a nonglycosylated monomeric protein of molecular mass 29 407 +/- 15 Da, which contains six cysteine residues engaged in the formation of three intramolecular disulfide bonds. Parkia platycephala lectin 2 agglutinated rabbit erythrocytes, and this activity was specifically inhibited by N-acetylglucosamine. In addition, Parkia platycephala lectin 2 hydrolyzed beta(1-4) glycosidic bonds linking 2-acetoamido-2-deoxy-beta-D-glucopyranose units in chitin. The full-lengthamino acid sequence of Parkia platycephala lectin 2, determined by N-terminal sequencing and cDNA cloning, and its three-dimensional structure, established by X-ray crystallography at 1.75 angstrom resolution, showed that Parkia platycephala lectin 2 is homologous to endochitinases of the glycosyl hydrolase family 18, which share the (beta alpha)(8) barrel topology harboring the catalytic residues Asp125, Glu127, and Tyr182.