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- ItemSomente MetadadadosDifferences in substrate specificities between cysteine protease CPB isoforms of Leishmania mexicana are mediated by a few amino acid changes(Blackwell Publishing Ltd, 2004-09-01) Juliano, Maria Aparecida [UNIFESP]; Brooks, Darren R.; Selzer, Paul M.; Pandolfo, Hector L.; Judice, Wagner AS; Juliano, Luiz [UNIFESP]; Meldal, Morten; Sanderson, Sanya J.; Mottram, Jeremy C.; Coombs, Graham H.; Univ Glasgow; Universidade Federal de São Paulo (UNIFESP); Intervet Innovat GmbH; Carlsberg Res LabThe CPB genes of the protozoan parasite Leishmania mexicana encode stage-regulated cathepsin L-like cysteine proteases that are important virulence factors and are in a tandem array of 19 genes. in this study, we have compared the substrate preferences of two CPB isoforms, CPB2.8 and CPB3, and a H84Y mutant of the latter enzyme, to analyse the roles played by the few amino acid differences between the isoenzymes in determining substrate specificity. CPB3 differs from CPB2.8 at just three residues (N60D, D61N and D64S) in the mature domain. the H84Y mutation mimics an additional change present in another isoenzyme, CPB18. the active recombinant CPB isoenzymes and mutant were produced using Escherichia coli and the S-1-S-3 and S-1'-S-3' subsite specificities determined using a series of fluorogenic peptide derivatives in which substitutions were made on positions P-3 to P-3' by natural amino acids. Carboxydipeptidase activities of CPB3 and H84Y were also observed using the peptide Abz-FRAK(Dnp)-OH and some of its analogues. the kinetic parameters of hydrolysis by CPB3, H84Y and CPB2.8 of the synthetic substrates indicates that the specificity of S-3 to S-3' subsites is influenced greatly by the modifications at amino acids 60, 61, 64 and 84. Particularly noteworthy was the large preference for Pro in the P-2' position for the hydrolytic activity of CPB3, which may be relevant to a role in the activation mechanism of the L. mexicana CPBs.
- ItemSomente MetadadadosDifferentiation of Leishmania major is impaired by over-expression of pyroglutamyl peptidase I(Elsevier B.V., 2006-12-01) Schaeffer, Marie; Miranda, Antonio de; Mottram, Jeremy C.; Coombs, Graham H.; Univ Glasgow; Universidade Federal de São Paulo (UNIFESP)Pyroglutamyl peptidases I (PPI) are cysteine peptidases of the clan CF, family C15, which hydrolyse N-terminal L-pyroglutamyl residues (L-pGlu). the L-pGlu modification is a post-transcriptional modification that confers relative aminopeptidase resistance and, in some cases, is essential to the modified peptides' biological activity. PPIs have been identified in a variety of organisms, although definitive biological functions have yet to be attributed to them. the L. major PPI was expressed in Escherichia coli as active recombinant enzyme, and shown to have biochemical properties more similar to mammalian than bacterial PPIs. the LmPPI active site catalytic triad of E101, C2 10, and H234 was confirmed by mutagenesis. PPI activity was detected in L. major promastigotes, and the enzyme localised to the parasite cytosol. No detectable phenotype could be observed for L. major PPI-deficient mutants, which retained infectivity to macrophages in vitro and mice. However, over-expression of the active PPI, but not inactive ppI(C210A), in L. major impaired differentiation from the procyclic promastigote to the infective metacyclic promastigote. Susceptibility to a natural L-pGlu-modified antimicrobial peptide, gomesin, was tested using the different cell lines, which were all equally susceptible. Whilst PPI is widespread through the eukaryotic kingdom, this study now suggests that the enzyme is not essential for normal eukaryotic cell function. However, PPI could be involved in regulating the action of L-pGlu-modified peptides required for differentiation of L. major. (c) 2006 Elsevier B.V. All rights reserved.
- ItemSomente MetadadadosImmune response to a major Trypanosoma cruzi antigen, cruzipain, is differentially modulated in C57BL/6 and BALB/c mice(Elsevier B.V., 2004-11-01) Guinazu, N.; Pellegrini, A.; Giordanengo, L.; Aoki, M. P.; Rivarola, H. W.; Cano, R.; Rodrigues, M. M.; Gea, S.; Univ Nacl Cordoba; Natl Univ Cordoba; Universidade Federal de São Paulo (UNIFESP)BALB/c mice immunized with cruzipain, a major Trypanosoma cruzi antigen, produce specific and autoreactive immune responses against heart myosin, associated with cardiac functional and structural abnormalities. Preferential activation of the Th2 phenotype and an increase in cell populations expressing CD19(+), Mac-1(+) and Gr-1(+) markers were found in the spleens of these mice. the aim of the present study was to investigate whether cardiac autoimmunity could be induced by cruzipain immunization of C57BL/6 mice and to compare the immune response elicited with that of BALB/c mice. We demonstrate that immune C57BL/6 splenocytes, re-stimulated in vitro with cruzipain, produced high levels of IFNgamma and low levels of IL-4 compatible with a Th1 profile. in contrast to BALB/c mice, spleens from cruzipain immune C57BL/6 mice revealed no significant changes in the number of cells presenting CD19(+), Mac-1(+) and Gr-1(+) markers. An increased secretion of TGFbeta and a greater number of CD4(+)TGFbeta(+) cells were found in immune C57BL/6 but not in BALB/c mice. These findings were associated with the lack of autoreactive response against heart myosin and a myosin- or cruzipain-derived peptide. Thus, the differential immune response elicited in C57BL/6 and BALB/c mice upon cruzipain immunization is implicated in the resistance or pathogenesis of experimental Chagas' disease. (C) 2004 Elsevier SAS. All rights reserved.
- ItemSomente MetadadadosA new species of Argulus (Crustacea, Branchiura, Argulidae) from the skin of catfish, with new records of branchiurans from wild fish in the Brazilian Pantanal wetland(Magnolia Press, 2017) Aguiar, Julio C.; Rosim, Daniele F.; Santos, Sonia M. C.; Luque, Jose L.; Ceccarelli, Paulo S.; Adriano, Edson A.; Tavares, Luiz E. R.During a survey conducted in the Cuiaba and Paraguay Rivers in the Brazilian Pantanal wetland, in the states of Mato Grosso and Mato Grosso do Sul, we found branchiurans associated with Pseudoplatystoma reticulatum, Pseudoplatystoma corruscans, Salminus brasiliensis and Zungaro zungaro. These branchiurans correspond to Argulus chiropteroideus sp. n., Argulus multicolor, Argulus nattereri, Argulus pestifer, Dolops carvalhoi and Dolops longicauda. Besides the description of the new species, in this study we also provide important morphological notes for diagnosis of the other species. Specimens of Argulus chiropteroideus sp. n. were collected from skin of P. reticulatum and P. corruscans. They differ from A. multicolor and Argulus chicomendesi, in the shape of the postantennal spines, which is medially convex and has two lateral and one anterior stout tips in the new species, and for having three claviform, digitate spines on the base of the second maxillae (absent in A. multicolor
- ItemSomente MetadadadosSmPKC1, a new protein kinase C identified in the platyhelminth parasite Schistosoma mansoni(Elsevier B.V., 2006-07-07) Bahia, Diana; Avelar, Livia; Mortara, Renato A.; Khayath, Naji; Yan, Yutao; Noel, Christophe; Capron, Monique; Dissous, Colette; Pierce, Raymond J.; Oliveira, Guilherme; Inst Pasteur; Fiocruz MS; Universidade Federal de São Paulo (UNIFESP); Newcastle Univ; Santa Casa Misericordia Belo HorizonteSchistosoma mansoni signal transduction pathways are promising sources of target molecules for the development of novel control strategies against this platyhelminth parasite of humans. Members of the protein kinase C (PKC) family play key roles in such pathways activated by both receptor tyrosine kinases and other receptors, controlling a variety of physiological processes. Here, we report the cloning and molecular characterization of the first PKC identified in S. mansoni. Structural analysis indicated that SmPKC1 exhibits all the features typical of the conventional PKC subfamily. the gene structure was determined in silico and found to comprise a total of 15 exons and 14 introns. This structure is highly conserved; all intron positions are also present in the human PKC beta gene and most of the exon sizes are identical. Using PCR on genomic DNA we were able to show that putative orthologues of SmPKC1 are present in 9 Schistosoma species. SmPKC1 expression is developmentally regulated with the highest level of transcripts in miracidia, whereas SmPKC1 protein expression is higher in the sporocyst. the localization of SmPKC1 on the sporocyst ridge cyton and in schistosomula acetabular glands suggests that the enzyme plays a role in signal transduction pathways associated with larval transformation. (c) 2006 Elsevier Inc. All rights reserved.
- ItemAcesso aberto (Open Access)Supplementary taxonomic description of Demidospermus pinirampi (Monogenoidea, Dactylogyridae), with a new host record and an expansion of its distribution range(Inst Nacional Pesquisas Amazonia, 2017) Cenci de Aguiar, Julio Cesar; Franco Bueno, Glauco Baptista; Cursino dos Santos, Sonia Maria; Adriano, Edson Aparecido [UNIFESP]During a survey conducted in the Lajeado Reservoir of the Tocantins River, in the state of Tocantins, Brazil, dactylogyrids were recovered from the gills of Pimelodina flavipinnis. Initial morphological analysis showed these dactylogyrids shared aspects of character with species of Demidospermus, with affinity to Demidospermus pinirampi, despite exhibiting differences with the original description by Kritsky et al. (1987) regarding the vagina, the base of the male copulatory organ and the shape and length of the bars. The analysis of the holotypes of D. pinirampi and its most morphologically close species, Demidospermus luckyi, revealed that these dactylogyrids were indeed D. pinirampi. This study therefore reports a new host and locality of occurrence, and reviews some measurements of the original description, supplementing and enhancing the morphological diagnosis of D. pinirampi.