[Show abstract][Hide abstract] ABSTRACT: The embryonic cuticle (EC) of Rhodnius prolixus envelopes the entire body of the embryo during hatching and provides physical protection, allowing the embryo to pass through a narrow chorionic border. Most of the knowledge about the EC of insects is derived from studies on ultrastructure and secretion processes during embryonic development, and little is known about the molecular composition of this structure. We performed a comprehensive molecular characterization of the major components extracted from the EC of R. prolixus, and we discuss the role of the different molecules that were identified during the eclosion process. The results showed that, similar to the post-embryonic cuticles of insects, the EC of R. prolixus is primarily composed of carbohydrates (57%), lipids (19%), and proteins (8%). Considering only the carbohydrates, chitin is by far the major component (approximately 70%), and it is found primarily along the body of the EC. It is scarce or absent in its prolongations, which are composed of glycosaminoglycans. In addition to chitin, we also identified amino (15%), neutral (12%) and acidic (3%) carbohydrates in the EC of R. prolixus. In addition carbohydrates, we also identified neutral lipids (64.12%) and phospholipids (35.88%). Proteomic analysis detected 68 proteins (55 were identified and 13 are hypothetical proteins) using the sequences in the non-annotated R. prolixus genome (http://www.vectorbase.org). Among these proteins, 8 out of 15 are associated with cuticle metabolism. These proteins are unequivocally cuticle proteins, and they have been described in other insects. Approximately 35% of the total proteins identified were classified as having a structural function. Chitin-binding protein, amino peptidase, amino acid oxidase, oxidoreductase, catalase and peroxidase are all proteins associated with cuticle metabolism. Proteins known to be cuticle constituents may be related to the function of the EC in assisting the insect during eclosion. To our knowledge, this is the first study to describe the global molecular composition of an EC in insects.
[Show abstract][Hide abstract] ABSTRACT: A joint transcriptomic and proteomic approach employing two-dimensional electrophoresis, liquid chromatography and mass spectrometry was carried out to identify peptides and proteins expressed by the venom gland of the snake Bothrops insularis, an endemic species of Queimada Grande Island, Brazil. Four protein families were mainly represented in processed spots, namely metalloproteinase, serine proteinase, phospholipase A(2) and lectin. Other represented families were growth factors, the developmental protein G10, a disintegrin and putative novel bradykinin-potentiating peptides. The enzymes were present in several isoforms. Most of the experimental data agreed with predicted values for isoelectric point and M(r) of proteins found in the transcriptome of the venom gland. The results also support the existence of posttranslational modifications and of proteolytic processing of precursor molecules which could lead to diverse multifunctional proteins. This study provides a preliminary reference map for proteins and peptides present in Bothrops insularis whole venom establishing the basis for comparative studies of other venom proteomes which could help the search for new drugs and the improvement of venom therapeutics. Altogether, our data point to the influence of transcriptional and post-translational events on the final venom composition and stress the need for a multivariate approach to snake venomics studies.
Journal of Proteomics 02/2009; 72(2):241-55. DOI:10.1016/j.jprot.2009.01.001 · 3.89 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Viral hemorrhagic fever is a clinical syndrome that poses serious global health threat. Among the causative agents, dengue virus (DV) has the highest incidence rate and its infection is the major cause of viral hemorrhagic fever in the world. Although the pathophysiological mechanisms of DV-induced diseases are not yet understood, it is well accepted that liver is a site of viral replication. In this study, we used proteomics to analyze infection of a hepatic cell lineage, HepG2, with DV, focusing on the secreted proteins. 1D-electrophoresis and liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) were used, allowing the identification of a total of 107 proteins, among which 35 were found only in control secretome and 24 only in infected cells secretome. To validate these data, we performed 2D-eletrophoresis followed by MALDI-TOF/TOF, resulting in the identification of 20 proteins, 8 of them confirming LC-MS/MS results. We discuss the results obtained taking into account the proteins previously described in the secretome of HepG2 cells, proteins present in human plasma and proteins of interest for dengue pathogenesis. Altogether the data presented here provide clues for the progress in the understanding of the role of liver secretion in the progression of the disease.
[Show abstract][Hide abstract] ABSTRACT: Snake venom C-type lectin-like proteins (CLPs) are ubiquitously found in Viperidae snake venoms and differ from the C-type lectins as they display different biological activities but no carbohydrate-binding activity. Previous analysis of the transcriptome obtained from the Bothrops insularis venom gland showed the presence of two clusters homologous to bothrojaracin (BJC) chains alpha and beta. In an effort to identify a new BJC-like molecule, we used an approach associated with proteomic technologies to identify the presence of the expressed protein and then to purify and characterize a new thrombin inhibitor from B. insularis venom. We also constructed homology models of this protein and BJC, which were compared with other C-type lectin-like family members and revealed several conserved features of this intriguing snake venom toxin family.
[Show abstract][Hide abstract] ABSTRACT: In mammals, hexokinase (HK) is strategically located at the outer membrane of mitochondria bound to the porin protein. The mitochondrial HK is a crucial modulator of apoptosis and reactive oxygen species generation. In plants, these properties related to HK are unknown. In order to better understand the physiological role of non-cytosolic hexokinase (NC-HK) in plants, we developed a purification strategy here described. Crude extract of 400 g of maize roots (230 mg protein) contained a specific activity of 0.042 micromol G6P min(-1) mg PTN(-1). After solubilization with detergent two fractions were obtained by DEAE column chromatography, NC-HK 1 (specific activity = 3.6 micromol G6P min(-1) mg PTN(-1) and protein recovered = 0.7 mg) and NC-HK 2. A major purification (yield = 500-fold) was obtained after passage of NC-HK 1 through the hydrophobic phenyl-Sepharose column. The total amount of protein and activity recovered were 0.04 and 18%, respectively. The NC-HK 1 binds to the hydrophobic phenyl-Sepharose matrix, as observed for rat brain HK. Mild chymotrypsin digestion did not affect adsorption of NC-HK 1 to the hydrophobic column as it does for rat HK I. In contrast to mammal mitochondrial HK, glucose-6-phosphate, clotrimazole or thiopental did not dissociate NC-HK from maize (Zea mays) or rice (Oryza sativa) mitochondrial membranes. These data show that the interaction between maize or rice NC-HK to mitochondria differs from that reported in mammals, where the mitochondrial enzyme can be displaced by modulators or pharmacological agents known to interfere with the enzyme binding properties with the mitochondrial porin protein.
Brazilian Journal of Medical and Biological Research 10/2006; 39(9):1159-69. DOI:10.1590/S0100-879X2006005000017 · 1.01 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The generation of expressed sequence tags (ESTs) from the pit-viper snake Lachesis muta venom glands allowed us to identify two cDNA isoforms which encode the precursors for bradykinin-potentiating peptides (BPPs) and a C-type natriuretic peptide (CNP). The sequence data derived from these cDNAs combined with the venom peptides identification using MALDI-TOF mass spectrometry analysis predicted that these molecules are the precursor protein isoforms that are further processed to produce five novel BPPs and a CNP. They were identified directly in crude venom using MALDI-TOF. The BPPs sequences were further confirmed by MALDI-TOF/TOF de novo sequencing, and an unusual BPP with a residue of tryptophan at the N-terminus (usually it is pyroglutamate) was identified. The putative processing steps required to form the mature BPPs and CNP seem to be similar to those proposed for the ones found in the venom of Bothrops jararaca and Glodyus blomhoffi.
[Show abstract][Hide abstract] ABSTRACT: Characterization of the peptide content in snake venoms can be an important tool for the investigation of new pharmacological lead compounds. For this purpose, single-step analysis of crude venoms has recently been demonstrated using mass spectrometry (MS) techniques. Reproducible profiles of ions in MS and MS/MS spectra may also be used to compare venoms from different species. In this work matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) was used to obtain mass patterns of the major peptides (<8 kDa) found in pooled venoms from the genera Bothrops and Crotalus. Venoms from five different Bothrops species (B. jararaca, B. insularis, B. alternatus, B. jararacussu, and B. neuwiedi) and three Crotalus species (C. viridis, C. adamanteus and C. durissus terrificus) were analyzed. In agreement with other reports, venoms from Bothrops species contained a variety of peptides in the range m/z 1000-1500, and in some samples larger components (m/z 7000-8000) were detected. In the Crotalus species venoms were rich in peptides ranging from m/z 1000-1500 and 4000-5500. MS/MS experiments on the low molecular mass peptides (m/z 1000-1500) confirmed the presence of ten new bradykinin-potentiating peptides among venoms from genera Bothrops and Crotalus. In order to determine whether additional peptides could be identified after partial purification, B. jararaca venom was subjected to size-exclusion chromatography on Sephacryl S-200, and two distinct low molecular mass pools were analyzed further by MALDI-TOFMS. No additional peptides were detected from the pool with masses below 2000 Da but a substantial improvement with better resolution was observed for the pool with masses above 7000 Da, indicating that complex samples such as crude snake venoms can be analyzed for low molecular mass peptides using a single-step procedure.
Rapid Communications in Mass Spectrometry 06/2005; 19(12):1703-8. DOI:10.1002/rcm.1973 · 2.25 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Lectins are carbohydrate-binding molecules that mediate a variety of biological processes. In this work, we identify and characterize a lectin from Bothrops insularis venom, with respect to its biochemical properties and theoretical structure. Initially, from a venom gland cDNA library, we cloned and sequenced a cDNA encoding a protein with high identity to snake venom lectins. A lectin molecule was purified to homogeneity from the venom by affinity column and gel filtration. This protein named BiL displayed hemagglutinating activity that was inhibited by galactose, lactose, and EDTA. Mass spectrometry analysis and sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed that BiL is a disulfide-linked dimeric protein consisting of monomers with 16,206 m/z. The amino acid sequence, deduced from its cDNA sequence, was confirmed by Edman sequencing and by peptide mass fingerprint analysis. BiL shows similarity to other C-type lectin family members. Modeling studies provide insights into BiL dimeric structure and its structural determinants for carbohydrate and calcium binding.
Archives of Biochemistry and Biophysics 01/2005; 432(1):1-11. DOI:10.1016/j.abb.2004.08.018 · 3.02 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: A new disintegrin, an RGD-containing peptide of 6 kDa called jarastatin, was purified from Bothrops jararaca venom. It is a potent inhibitor of platelet aggregation induced by ADP, collagen, and thrombin. The effect of jarastatin on neutrophil migration in vivo and in vitro and on the actin cytoskeleton dynamics of these cells was investigated. Incubation in vitro with jarastatin significantly inhibited, in a concentration-dependent manner, the chemotaxis of human neutrophils toward fMLP, IL-8, and jarastatin itself. Despite this inhibitory effect, jarastatin induced neutrophil chemotaxis. A significant increase of F-actin content was observed in jarastatin-treated neutrophils. Furthermore, as demonstrated by confocal microscopy after FITC-phalloidin labeling, these cells accumulated F-actin at the plasmalemma, a distribution similar to that observed in fMLP-stimulated cells. Pretreatment of mice with jarastatin inhibited neutrophil migration into peritoneal cavities induced by carrageenan injection. The results suggest that binding of jarastatin to neutrophil integrins promotes cellular activation and triggers a dynamic alteration of the actin filament system and that this is one of the first event in integrin-mediated signaling.
Experimental Cell Research 10/1999; 251(2):379-87. DOI:10.1006/excr.1999.4583 · 3.25 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Bothroalternin (MW 27 kDa), a new member of the family of C-type lectins is a thrombin inhibitor which was purified from pooled B. alternatus venom by affinity chromatography on PPACK-thrombin-Sepharose, followed by size exclusion and reverse-phase on HPLC columns. Material retained on the affinity column contained proteins with apparent molecular weights ranging from 20 to 60 kDa on SDS-PAGE and inhibited aggregation of rabbit platelets induced by alpha-thrombin (IC50 = 28 microg/ml). A single band of approximately 27 kDa was recognized in Western-blot assays using polyclonal antibodies raised against bothrojaracin, a thrombin inhibitor purified from B. jararaca venom (Zingali et al., 1993). The immunological similarity of this fraction to bothrojaracin was confirmed by ELISA and competitive ELISA. Further purification by size exclusion and reverse-phase on HPLC, produced a single homogenous peak called bothroalternin. This protein was highly homologous to bothrojaracin (95% in its N-terminal sequence-for residues 1 to 25) but displaying lower inhibitory effect on thrombin induced platelet aggregation (Ic50 = 0.19 microg/ml) compared to bothrojaracin (IC50 = 0.06). Altogether, bothroalternin is a new thrombin inhibitor isolated from Bothrops alternatus venom and has been characterized as a bothrojaracin-like protein.
[Show abstract][Hide abstract] ABSTRACT: Snake venoms usually contain multiple molecular forms of phospholipase A2 enzymes (phosphatide acyl hydrolase, E.C. 184.108.40.206; PLA2). Phospholipases A2 induce a wide range of pharmacological effects which may depend or not on the hydrolysis of phospholipids. In this study, a PLA2 from Bothrops jararaca venom was purified to homogeneity by gel filtration on a Sephacryl S-200 column, followed by FPLC reverse-phase chromatography on a Pep-RPC HR 5/5 column (yield 1.63% of venom protein). The PLA2 activity of the fractions was determined by indirect hemolysis using hen's egg yolk lecithin as substrate. The enzyme is an acidic protein with PI 4.5 and an apparent molecular weight of 14,200, as estimated by gel filtration on a Superose 12 FPLC column. Similar properties have been described for PLA2 from other snake venoms. The N-terminal-sequence of the purified protein was NLMQFETMIMXXAGQ. These partial sequence data show a high degree of homology between the B. jararaca PLA2 and the enzymes from other snake venoms as well as bovine pancreatic PLA2.
Brazilian Journal of Medical and Biological Research 03/1993; 26(2):163-6. · 1.01 Impact Factor