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Sent on Tuesday, 2010 Jan 05Search kinetoplastids OR kinetoplastid OR Kinetoplastida OR "trypanosoma brucei" OR leishmania OR brucei OR leishmaniasis OR "African trypanosomiasis"
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| PubMed Results |
| 1. | Exp Parasitol. 2009 Dec 31. [Epub ahead of print]Leishmania amazonensis: Heme stimulates (Na(+)+K(+))ATPase activity via phosphatidylinositol-specific phospholipase C /Protein Kinase C-like (PI-PLC/PKC) signaling pathways.Almeida-Amaral EE, Cardoso VC, Francioli FG, Meyer-Fernandes JR.Laboratório de Bioquímica de Tripanosomatideos, Instituto Oswaldo Cruz, Fundação Oswaldo Cruz - FIOCRUZ, Pavilhão Leônidas Deane, 4 degrees andar, sala 405, Manguinhos, 21045-900, Rio de Janeiro, RJ, Brazil. In the present paper we studied the involvement of the phosphatidylinositol-specific PLC (PI-PLC)/protein kinase C (PKC) pathway in (Na(+)+K(+))ATPase stimulation by heme in L. amazonensis promastigotes. Heme stimulated the PKC-like activity with a concentration of 50 nM. Interestingly, the maximal stimulation of the PKC-like activity promoted by phorbol ester was of the same magnitude promoted by heme. However, the stimulatory effect of heme is completely abolished by ET-18-OCH(3) and U73122, specific inhibitors of PI-PLC. (Na(+)+K(+))ATPase activity is increased in the presence of increased concentrations of heme, being maximally affected at 50 nM. This effect was completely reversed by 10 nM calphostin C, an inhibitor of PKC. Thus, the effect of 50 nM heme on (Na(+)+K(+))ATPase activity is completely abolished by ET-18-OCH(3) and U73122. Taken together, these results demonstrate that the heme receptor mediates the stimulatory effect of heme on the (Na(+)+K(+))ATPase activity through a PI-PLC/PKC signaling pathway. Copyright © 2009. Published by Elsevier Inc. |
| PMID: 20045694 [PubMed - as supplied by publisher] | |
| 2. | Exp Cell Res. 2009 Dec 31. [Epub ahead of print]The Small Ubiqutin-Like Modifier (SUMO) is Essential in Cell Cycle Regulation in Trypanosoma brucei.Liao S, Wang T, Fan K, Tu X.Hefei National Laboratory for Physical Sciences at Microscale, School of Life Science, University of Science and Technology of China, Hefei, Anhui 230026, P.R. China. SUMO, a reversible post-translational protein modifier, plays important roles in many processes of higher eukaryotic cell life. Although SUMO has been identified in many eukaryotes, SUMO and SUMO system are still unknown in some eukaryotic unicellular organisms, such as Trypanosoma brucei (T. brucei). In this study, only one SUMO homologue (TbSUMO) was identified in T. brucei. Expression of TbSUMO was knocked down by using RNA interference technique in procyclic-form T. brucei. The growth of TbSUMO-deficient cells was significantly inhibited. TbSUMO-deficient cells were arrested in G(2)/M phase accompanied with an obvious increase of 0N1K cells (zoids), and failed in chromosome segregation. These results indicate that TbSUMO is essential in cell cycle regulation, with one important role in mitosis. Meanwhile, the enrichment of zoids suggests the inhibition of mitosis doesn't prevent the cell division in procyclic-form T. brucei. HA-tagged TbSUMO was overexpressed in T. brucei and was shown to be localized to the nucleus through the whole cell cycle, further revealing its distinguished functions in nucleus. All these accumulated data imply that a SUMO system essential for regulating cell cycle progression might exist in the procyclic-form T. brucei. Copyright © 2009 Elsevier Inc. All rights reserved. |
| PMID: 20045687 [PubMed - as supplied by publisher] | |
| 3. | Mol Biochem Parasitol. 2009 Dec 30. [Epub ahead of print]Structure of Trypanosoma brucei glutathione synthetase; domain and loop alterations in the catalytic cycle of a highly conserved enzyme.Fyfe PK, Alphey MS, Hunter WN.Division of Biological Chemistry and Drug Discovery, College of Life Sciences, University of Dundee, Dow Street, Dundee, DD1 5EH, United Kingdom. Glutathione synthetase catalyses the synthesis of the low molecular mass thiol glutathione from L-gamma-glutamyl-L-cysteine and glycine. We report the crystal structure of the dimeric enzyme from Trypanosoma brucei in complex with the product glutathione. The enzyme belongs to the ATP-grasp family, a group of enzymes known to undergo conformational changes upon ligand binding. The T. brucei enzyme crystal structure presents two dimers in the asymmetric unit. The structure reveals variability in the order and position of a small domain, which forms a lid for the active site and serves to capture conformations likely to exist during the catalytic cycle. Comparisons with orthologous enzymes, in particular from Homo sapiens and Saccharomyces cerevisae, indicate a high degree of sequence and structure conservation in part of the active site. Structural differences that are observed between the orthologous enzymes are assigned to different ligand binding states since key residues are conserved. This suggests that the molecular determinants of ligand recognition and reactivity are highly conserved across species. We conclude that it would be difficult to target the parasite enzyme in preference to the host enzyme and therefore glutathione synthetase may not be a suitable target for antiparasitic drug discovery. Copyright © 2009. Published by Elsevier B.V. |
| PMID: 20045436 [PubMed - as supplied by publisher] | |
| 4. | Colloids Surf B Biointerfaces. 2009 Dec 1;74(2):504-10. Epub 2009 Aug 18.The interaction of an antiparasitic peptide active against African sleeping sickness with cell membrane models.Pascholati CP, Lopera EP, Pavinatto FJ, Caseli L, Nobre TM, Zaniquelli ME, Viitala T, D'Silva C, Oliveira ON Jr.Instituto de Física de São Carlos, Universidade de São Paulo, 13560-970 São Carlos, SP, Brazil. Zwitterionic peptides with trypanocidal activity are promising lead compounds for the treatment of African Sleeping Sickness, and have motivated research into the design of compounds capable of disrupting the protozoan membrane. In this study, we use the Langmuir monolayer technique to investigate the surface properties of an antiparasitic peptide, namely S-(2,4-dinitrophenyl)glutathione di-2-propyl ester, and its interaction with a model membrane comprising a phospholipid monolayer. The drug formed stable Langmuir monolayers, whose main feature was a phase transition accompanied by a negative surface elasticity. This was attributed to aggregation upon compression due to intermolecular bond associations of the molecules, inferred from surface pressure and surface potential isotherms, Brewster angle microscopy (BAM) images, infrared spectroscopy and dynamic elasticity measurements. When co-spread with dipalmitoyl phosphatidyl choline (DPPC), the drug affected both the surface pressure and the monolayer morphology, even at high surface pressures and with low amounts of the drug. The results were interpreted by assuming a repulsive, cooperative interaction between the drug and DPPC molecules. Such repulsive interaction and the large changes in fluidity arising from drug aggregation may be related to the disruption of the membrane, which is key for the parasite killing property. |
| PMID: 19729286 [PubMed - indexed for MEDLINE] | |
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