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

AbstractCanavalia 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.© 1997 Federation of European Biochemical Societies

Variant vicilins from a resistant Vigna unguiculata lineage (IT81D-1053)\ud accumulate inside Callosobruchus maculatus larval midgut epithelium

It has been demonstrated that variant vicilins are the main resistance factor of cowpea seeds (Vigna unguiculata) against attack by the cowpea beetle Callosobruchus maculatus. There is evidence that the toxic properties of these storage proteins may be related to their interaction with glycoproteins and other microvillar membrane constituents along the digestive tract of the larvae. New findings have shown that following interaction with the microvilli, the vicilins are absorbed across the intestinal epithelium and thus reach the internal environment of the larvae. In the present paper we studied the insecticidal activity of the variant vicilins purified from a resistant cowpea variety (IT81D-1053). Bioassays showed that the seeds of this genotype affected larval growth, causing developmental retardation and 100% mortality. By feeding C. maculatus larvae on susceptible and IT81D-1053 derived vicilins (FITC labelled or unlabelled), followed by fluorescence and immunogold cytolocalization, we were able to demonstrate that both susceptible and variant forms are internalized in the midgut cells and migrate inside vesicular structures from the apex to the basal portion of the enterocytes. However, when larvae were fed with the labelled vicilins for 24 h and then returned to a control diet, the concentration of the variant form remained relatively high, suggesting that variant vicilins are not removed from the cells at the same rate as the non-variant vicilins. We suggest that the toxic effects of variant vicilins on midgut cells involve the binding of these proteins to the cell surface followed by internalization and interference with the normal physiology of the enterocytes, thereby affecting larval development in vivo

Phylogenetic relationships within Chamaecrista sect. Xerocalyx (Leguminosae, Caesalpinioideae) inferred from the cpDNA trnE-trnT intergenic spacer and nrDNA ITS sequences

Chamaecrista belongs to subtribe Cassiinae (Caesalpinioideae), and it comprises over 330 species, divided into six sections. The section Xerocalyx has been subjected to a profound taxonomic shuffling over the years. Therefore, we conducted a phylogenetic analysis using a cpDNA trnE-trnT intergenic spacer and nrDNA ITS/5.8S sequences from Cassiinae taxa, in an attempt to elucidate the relationships within this section from Chamaecrista. The tree topology was congruent between the two data sets studied in which the monophyly of the genus Chamaecrista was strongly supported. Our analyses reinforce that new sectional boundaries must be defined in the Chamaecrista genus, especially the inclusion of sections Caliciopsis and Xerocalyx in sect. Chamaecrista, considered here paraphyletic. The section Xerocalyx was strongly supported as monophyletic; however, the current data did not show C. ramosa (microphyllous) and C. desvauxii (macrophyllous) and their respective varieties in distinct clades, suggesting that speciation events are still ongoing in these specimens

The complete genome sequence of Chromobacterium violaceum reveals remarkable and exploitable bacterial adaptability

Chromobacterium violaceum is one of millions of species of free-living microorganisms that populate the soil and water in the extant areas of tropical biodiversity around the world. Its complete genome sequence reveals (i) extensive alternative pathways for energy generation, (ii) ≈500 ORFs for transport-related proteins, (iii) complex and extensive systems for stress adaptation and motility, and (iv) wide-spread utilization of quorum sensing for control of inducible systems, all of which underpin the versatility and adaptability of the organism. The genome also contains extensive but incomplete arrays of ORFs coding for proteins associated with mammalian pathogenicity, possibly involved in the occasional but often fatal cases of human C. violaceum infection. There is, in addition, a series of previously unknown but important enzymes and secondary metabolites including paraquat-inducible proteins, drug and heavy-metal-resistance proteins, multiple chitinases, and proteins for the detoxification of xenobiotics that may have biotechnological applications

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

Expression and purification of the recombinant ConBr (Canavalia brasiliensis lectin) produced in Escherichia coli cells

Submitted by Ana Maria Fiscina Sampaio ([email protected]) on 2014-03-24T16:37:27Z No. of bitstreams: 1 Nogueira N A Expression and Purification....pdf: 171605 bytes, checksum: d6d7da12c44cdb5001ae6efbed408a44 (MD5)Made available in DSpace on 2014-03-24T16:37:27Z (GMT). No. of bitstreams: 1 Nogueira N A Expression and Purification....pdf: 171605 bytes, checksum: d6d7da12c44cdb5001ae6efbed408a44 (MD5) Previous issue date: 2002Universidade Federal do Ceará. Departamento de Analises Clínicas e Toxicológicas. Fortaleza, CE, BrasilUniversidade Federal do Ceará. Laboratório de Citogenética e Genética Molecular. Departamento de Biologia. Centro de Ciências. Fortaleza, CE, BrasilUniversidade Federal do Ceará. Laboratório de Citogenética e Genética Molecular. Departamento de Biologia. Centro de Ciências. Fortaleza, CE, BrasilUniversidade Federal do Ceará. Departamento de Biologia. Fortaleza, CE, BrasilUniversidade Federal do Ceará. Laboratório de Citogenética e Genética Molecular. Departamento de Biologia. Centro de Ciências. Fortaleza, CE, BrasilUniversidade Federal do Ceará. BioMol-Laboratório. Departamento de Bioquímica e Biologia Molecular. Fortaleza, CE, BrasilFundação Oswaldo Cruz. Centro de Pesquisa Gonçalo Moniz. Salvador, BA, BrasilCIB, CSIC, Madrid, SpainUniversidade Federal do Ceará. BioMol-Laboratório. Departamento de Bioquímica e Biologia Molecular. Fortaleza, CE, BrasilUniversidade Federal do Ceará. Laboratório de Citogenética e Genética Molecular. Departamento de Biologia. Centro de Ciências. Fortaleza, CE, BrasilConBr, a D-glucose/D-mannose-specific lectin from Canavalia brasiliensis seeds, was produced in Escherichia coli from a cDNA clone subcloned to pET15b expression vector. The recombinant lectin (rConBr) was purified by onestep immobilized metal-affinity chromatography using an amino-terminal hexahistidine tag. By SDS-PAGE and Western blot, rConBr was highly pure with an apparent molecular mass of 37 kDa. N-terminal sequence analysis revealed a single sequence, confirming the identity of the expressed protein as the pre-pro-ConBr

Food safety assessment of an antifungal protein from Moringa oleifera seeds in an agricultural biotechnology perspective

AbstractMo-CBP3 is an antifungal protein produced by Moringa oleifera which has been investigated as potential candidate for developing transgenic crops. Before the use of novel proteins, food safety tests must be conducted. This work represents an early food safety assessment of Mo-CBP3, using the two-tiered approach proposed by ILSI. The history of safe use, mode of action and results for amino acid sequence homology using the full-length and short contiguous amino acids sequences indicate low risk associated to this protein. Mo-CBP3 isoforms presented a reasonable number of alignments (>35% identity) with allergens in a window of 80 amino acids. This protein was resistant to pepsin degradation up to 2 h, but it was susceptible to digestion using pancreatin. Many positive attributes were presented for Mo-CBP3. However, this protein showed high sequence homology with allergens and resistance to pepsin digestion that indicates that further hypothesis-based testing on its potential allergenicity must be done. Additionally, animal toxicity evaluations (e.g. acute and repeated dose oral exposure assays) must be performed to meet the mandatory requirements of several regulatory agencies. Finally, the approach adopted here exemplified the importance of performing an early risk assessment of candidate proteins for use in plant transformation programs

Antimicrobial Effects of Violacein against Planktonic Cells and Biofilms of Staphylococcus aureus

Violacein is an indole compound, produced by Chromobacterium violaceum, a bacteria present in tropical and subtropical areas. Among its numerous biological activities, its antimicrobial potential stands out. This study aims to determine the antimicrobial activity of VIO on S. aureus in planktonic culture and biofilms. VIO showed excellent antimicrobial activity in inhibiting and killing S. aureus in planktonic cultures and biofilm formation. The minimum bactericidal concentration (5 μg/mL) of VIO caused the death of S. aureus after 3–4 h of exposure and the minimum inhibitory concentration (1.25 μg/mL) of VIO inhibited bacterial growth within the first 8 h of contact. Biofilm formation was also strongly inhibited by VIO (1.25 μg/mL), in contrast to the higher resistance verified for S. aureus in mature biofilm (40 μg/mL). The high bacterial metabolic activity favored VIO activity; however, the good activity observed during phases of reduced metabolism indicates that VIO action involves more than one mechanism. Thus, VIO is a promising molecule for the development of an antimicrobial drug for the eradication of S. aureus infections