| an essential quality control mechanism at the eukaryotic basal body prior to intraflagellar transport. | constructing a eukaryotic cilium/flagellum is a demanding task requiring the transport of proteins from their cytoplasmic synthesis site into a spatially and environmentally distinct cellular compartment. the clear potential hazard is that import of aberrant proteins could seriously disable cilia/flagella assembly or turnover processes. here, we reveal that tubulin protein destined for incorporation into axonemal microtubules interacts with a tubulin cofactor c (tbcc) domain-containing protein t ... | 2007 | 17645436 |
| pentatricopeptide repeat proteins in trypanosoma brucei function in mitochondrial ribosomes. | the pentatricopeptide repeat (ppr), a degenerate 35-amino-acid motif, defines a novel eukaryotic protein family. plants have 400 to 500 distinct ppr proteins, whereas other eukaryotes generally have fewer than 5. the few ppr proteins that have been studied have roles in organellar gene expression, probably via direct interaction with rna. here we show that the parasitic protozoan trypanosoma brucei encodes 28 distinct ppr proteins, an extraordinarily high number for a nonplant organism. a compar ... | 2007 | 17646387 |
| type 3 peptide deformylases are required for oxidative phosphorylation in trypanosoma brucei. | peptide deformylase (pdf) catalyses the removal of the formyl group from the first methionine of nascent proteins. type 1 pdfs are found in bacteria and have orthologues in most eukaryotes. type 2 pdfs are restricted to bacteria. type 3 enzymes are found in archaea and trypanosomatids and have not been studied experimentally yet. thus, tbpdf1 and tbpdf2, the two pdf orthologues of the parasitic protozoa trypanosoma brucei, are of type 3. an experimental analysis of these enzymes shows that both ... | 2007 | 17651388 |
| analysis of the vsg gene silent archive in trypanosoma brucei reveals that mosaic gene expression is prominent in antigenic variation and is favored by archive substructure. | trypanosoma brucei evades host acquired immunity through differential activation of its large archive of silent variant surface glycoprotein (vsg) genes, most of which are pseudogenes in subtelomeric arrays. we have analyzed 940 vsgs, representing one half to two thirds of the arrays. sequence types a and b of the vsg n-terminal domains were confirmed, while type c was found to be a constituent of type a. two new c-terminal domain types were found. nearly all combinations of domain types occurre ... | 2007 | 17652423 |
| correlative light and electron microscopy using immunolabeled resin sections. | in correlative microscopy, light microscopy provides the overview and orientation in the complex cells and tissue, whereas electron microscopy offers the detailed localization and correlation to subcellular structures. in this chapter, we offer the detailed high-quality electron microscopical preparation methods for the optimum preservation of the cellular ultrastructure. from such preparations, serial thin sections are collected and used for comparative histochemical, immunofluorescence, and im ... | 2007 | 17656754 |
| trypanosoma brucei polo-like kinase is essential for basal body duplication, kdna segregation and cytokinesis. | polo-like kinases (plks) are conserved eukaryotic cell cycle regulators, which play multiple roles, particularly during mitosis. the function of trypanosoma brucei plk was investigated in procyclic and bloodstream-form parasites. in procyclic trypanosomes, rna interference (rnai) of plk, or overexpression of ty1-epitope-tagged plk (plkty), but not overexpression of a kinase-dead variant, resulted in the accumulation of cells that had divided their nucleus but not their kinetoplast (2n1k cells). ... | 2007 | 17662039 |
| gene conversion is a convergent strategy for pathogen antigenic variation. | recent studies on three unrelated vector-borne pathogens, anaplasma marginale, borrelia hermsii and trypanosoma brucei, illustrate the central importance of gene conversion as a mechanism for antigenic variation, which results in subsequent evasion of the immune response and persistence in the reservoir host. the combination of genome sequence data and in vivo studies tracking variant emergence not only provides insight into the genetic mechanisms for variant generation and hierarchy in variant ... | 2007 | 17662656 |
| isolation and compositional analysis of trypanosomatid editosomes. | most mitochondrial (mt) mrnas in trypanosomes undergo posttranscriptional rna editing, which inserts and deletes uridines (us) to produce the mature and functional mrna. the editing process is catalyzed by multiple enzymatic steps and is carried out by an approximately 20s macromolecular complex, the editosome. editosomes have been purified from trypanosoma brucei using various techniques including combinations of column chromatography, gradient sedimentation, monoclonal antibody affinity, and t ... | 2007 | 17662834 |
| uridine insertion/deletion editing activities. | the uridine nucleotide insertion and deletion editing of trypanosomatid mitochondrial mrnas is catalyzed by a macromolecular complex, the editosome. many investigations of rna editing involve some assessment of editosome activity either in vitro or in vivo. assays to detect insertion or deletion editing activity on rnas in vitro have been particularly useful, and can include the initial endonucleolytic step (full-round) or bypass it (precleaved). additional assays to examine individual catalytic ... | 2007 | 17662835 |
| rna editing uridylyltransferases of trypanosomatids. | terminal rna uridylyltransferases (tutases) catalyze the transfer of ump residues to the 3' hydroxyl group of rna. these enzymes belong to the dna polymerase beta superfamily, which also includes poly(a) polymerases, cca-adding enzymes, and other nucleotidyltransferases. studies of uridylyl insertion/deletion rna editing in mitochondria of trypanosomatids provided the first examples of biological functions for tutases: posttranscriptional uridylylation of guide rnas by rna editing tutase 1 (ret1 ... | 2007 | 17662836 |
| isolation of rna binding proteins involved in insertion/deletion editing. | rna editing is a collective term referring to a plethora of reactions that ultimately lead to changes in rna nucleotide sequences apart from splicing, 5' capping, or 3' end processing. in the mitochondria of trypanosomatids, insertion and deletion of uridines must occur, often on a massive scale, in order to generate functional messenger rnas. the current state of knowledge perceives the editing machinery as a dynamic system, in which heterogeneous protein complexes undergo multiple transient rn ... | 2007 | 17662837 |
| rna-protein interactions in assembled editing complexes in trypanosomes. | multisubunit rna editing complexes recognize thousands of pre-mrna sites in the single mitochondrion of trypanosomes. specific determinants at each editing site must trigger the complexes to catalyze a complete cycle of either uridylate insertion or deletion. while a wealth of information on the protein composition and catalytic activities of these complexes is currently available, the precise mechanisms that govern substrate recognition and editing site specificity remain unknown. this chapter ... | 2007 | 17662838 |
| functional genomics and immunological approaches toward a comprehensive view of protozoan parasite virulence factors. | | 2007 | 17678416 |
| tbarf1 influences lysosomal function but not endocytosis in procyclic stage trypanosoma brucei. | the adp ribosylation factors (arfs) are a highly conserved subfamily of the ras small gtpases with crucial roles in vesicle budding and membrane trafficking. unlike in other eukaryotes, the orthologue of arf1 in the host bloodstream form of trypanosoma brucei is essential for the maintenance of endocytosis. in contrast, as shown in this study, knockdown of tbarf1 by rna interference has no effect on fluid-phase endocytosis in the insect stage of the parasite. the protein remains essential for th ... | 2007 | 17681620 |
| antiproliferative effect of dihydroxyacetone on trypanosoma brucei bloodstream forms: cell cycle progression, subcellular alterations, and cell death. | we evaluated the effects of dihydroxyacetone (dha) on trypanosoma brucei bloodstream forms. dha is considered an energy source for many different cell types. t. brucei takes up dha readily due to the presence of aquaglyceroporins. however, the parasite is unable to use it as a carbon source because of the absence of dha kinase (dhak). we could not find a homolog of the relevant gene in the genomic database of t. brucei and have been unable to detect dhak activity in cell lysates of the parasite, ... | 2007 | 17682096 |
| the hydrocephalus inducing gene product, hydin, positions axonemal central pair microtubules. | impairment of cilia and flagella function underlies a growing number of human genetic diseases. mutations in hydin in hy3 mice cause lethal communicating hydrocephalus with early onset. hydin was recently identified as an axonemal protein; however, its function is as yet unknown. | 2007 | 17683645 |
| ku heterodimer-independent end joining in trypanosoma brucei cell extracts relies upon sequence microhomology. | dna double-strand breaks (dsbs) are repaired primarily by two distinct pathways: homologous recombination and nonhomologous end joining (nhej). nhej has been found in all eukaryotes examined to date and has been described recently for some bacterial species, illustrating its ancestry. trypanosoma brucei is a divergent eukaryotic protist that evades host immunity by antigenic variation, a process in which homologous recombination plays a crucial function. while homologous recombination has been e ... | 2007 | 17693593 |
| differential expression of fat body genes in glossina morsitans morsitans following infection with trypanosoma brucei brucei. | to determine which fat body genes were differentially expressed following infection of glossina morsitans morsitans with trypanosoma brucei brucei we generated four suppression subtractive hybridisation (ssh) libraries. we obtained 52 unique gene fragments (ssh clones) of which 30 had a known orthologue at e-05 or less. overall the characteristics of the orthologues suggest: (i) that trypanosome infection has a considerable effect on metabolism in the tsetse fly; (ii) that self-cured flies are m ... | 2008 | 17697681 |
| epimers of bicyclo[2.2.2]octan-2-ol derivatives with antiprotozoal activity. | (2sr,6rs,7rs)-4-dialkylaminobicyclo[2.2.2]octan-2-ols and several of their esters have shown promising activity against the causative organisms for malaria and sleeping sickness. the base-catalyzed epimerization of the alcohols was carried out by different methods giving their (2rs,6rs,7rs)-isomers. best results were obtained by the consecutive use of potassium tert-butoxide and sodium. the isomeric alcohols were converted to selected esters. all new compounds were tested for their activity agai ... | 2008 | 17698258 |
| adenosine kinase of trypanosoma brucei and its role in susceptibility to adenosine antimetabolites. | trypanosoma brucei cannot synthesize purines de novo and relies on purine salvage from its hosts to build nucleic acids. with adenosine being a preferred purine source of bloodstream-form trypanosomes, adenosine kinase (ak; ec 2.7.1.20) is likely to be a key player in purine salvage. adenosine kinase is also of high pharmacological interest, since for many adenosine antimetabolites, phosphorylation is a prerequisite for activity. here, we cloned and functionally characterized adenosine kinase fr ... | 2007 | 17698621 |
| 2,n6-disubstituted adenosine analogs with antitrypanosomal and antimalarial activities. | a library of 2,n(6)-disubstituted adenosine analogs was synthesized and the analogs were tested for their antiprotozoal activities. it was found that 2-methoxy and 2-histamino and n(6)-m-iodobenzyl substitutions generally produced analogs with low levels of antiprotozoal activity. the best antiplasmodial activity was achieved with large aromatic substitutions, such as n(6)-2,2-diphenylethyl and naphthylmethyl, which could indicate a mechanism of action through aromatic stacking with heme in the ... | 2007 | 17698622 |
| uridylate-specific 3' 5'-exoribonucleases involved in uridylate-deletion rna editing in trypanosomatid mitochondria. | in kinetoplastid protists, maturation of mitochondrial pre-mrnas involves the insertion and deletion of uridylates (us) within coding regions, as specified by mitochondrial dna-encoded guide rnas. u-deletion editing involves endonucleolytic cleavage of the pre-mrna at the editing site followed by u-specific 3'-5'-exonucleolytic removal of nonbase-paired us prior to ligation of the two mrna cleavage fragments. we showed previously that an exonuclease/endonuclease/phosphatase (eep) motif protein f ... | 2007 | 17699520 |
| genetic characterisation of trypanosoma brucei s.l. using microsatellite typing: new perspectives for the molecular epidemiology of human african trypanosomiasis. | the pathogenic agent of human african trypanosomiasis (hat) is a trypanosome belonging to the species trypanosoma brucei s.l. molecular methods developed for typing t. brucei s.l. stocks are for the most part not polymorphic enough to study genetic diversity within t. brucei gambiense (t. b. gambiense) group 1, the main agent of hat in west and central africa. furthermore, these methods require high quantities of parasite material and consequently are hampered by a selection bias of the isolatio ... | 2007 | 17704009 |
| jbp2, a swi2/snf2-like protein, regulates de novo telomeric dna glycosylation in bloodstream form trypanosoma brucei. | synthesis of the modified thymine base, beta-d-glucosyl-hydroxymethyluracil or j, within telomeric dna of trypanosoma brucei correlates with the bloodstream form specific epigenetic silencing of telomeric variant surface glycoprotein genes involved in antigenic variation. in order to analyze the function of base j in the regulation of antigenic variation, we are characterizing the regulatory mechanism of j biosynthesis. we have recently proposed a model in which chromatin remodeling by a swi2/sn ... | 2007 | 17706299 |
| quinuclidine derivatives as potential antiparasitics. | there is an urgent need for the development of new drugs for the treatment of tropical parasitic diseases such as chagas' disease and leishmaniasis. one potential drug target in the organisms that cause these diseases is sterol biosynthesis. this paper describes the design and synthesis of quinuclidine derivatives as potential inhibitors of a key enzyme in sterol biosynthesis, squalene synthase (sqs). a number of compounds that were inhibitors of the recombinant leishmania major sqs at submicrom ... | 2007 | 17709461 |
| histone modifications in trypanosoma brucei. | several biological processes in trypanosoma brucei are affected by chromatin structure, including gene expression, cell cycle regulation, and life-cycle stage differentiation. in saccharomyces cerevisiae and other organisms, chromatin structure is dependent upon posttranslational modifications of histones, which have been mapped in detail. the tails of the four core histones of t. brucei are highly diverged from those of mammals and yeasts, so sites of potential modification cannot be reliably i ... | 2007 | 17714803 |
| two trypanosome-specific proteins are essential factors for 5s rrna abundance and ribosomal assembly in trypanosoma brucei. | we have previously identified and characterized two novel nuclear rna binding proteins, p34 and p37, which have been shown to bind 5s rrna in trypanosoma brucei. these two proteins are nearly identical, with one major difference, an 18-amino-acid insert in the n-terminal region of p37, as well as three minor single-amino-acid differences. homologues to p34 and p37 have been found only in other trypanosomatids, suggesting that these proteins are unique to this ancient family. we have employed rna ... | 2007 | 17715362 |
| down-regulation of the trypanosomatid signal recognition particle affects the biogenesis of polytopic membrane proteins but not of signal peptide-containing proteins. | protein translocation across the endoplasmic reticulum is mediated by the signal recognition particle (srp). in this study, the srp pathway in trypanosomatids was down-regulated by two approaches: rna interference (rnai) silencing of genes encoding srp proteins in trypanosoma brucei and overexpression of dominant-negative mutants of 7sl rna in leptomonas collosoma. the biogenesis of both signal peptide-containing proteins and polytopic membrane proteins was examined using endogenous and green fl ... | 2007 | 17715370 |
| in vitro and in vivo evaluation of the antitrypanosomal activity of fractions of holarrhena africana. | the aqueous extract of young leaves of holarrhena africana, a plant used in the nigerian traditional medicine, exhibited good activity against trypanosoma brucei spp. the extract was fractionated and eight fractions were obtained. one fraction designated as haf(5) showed in vitro activity against trypanosoma brucei rhodesiense with an ic(50) value of 0.785 microg/mg and no overt cytotoxicity against l-6 cells. fraction haf(5) was tested in vivo at two doses and found to exhibit in vivo efficacy ... | 2007 | 17728085 |
| dual role of the rna substrate in selectivity and catalysis by terminal uridylyl transferases. | terminal rna uridylyltransferases (tutases) catalyze template-independent ump addition to the 3' hydroxyl of rna. tutases belong to the dna polymerase beta superfamily of nucleotidyltransferases that share a conserved catalytic domain bearing three metal-binding carboxylate residues. we have previously determined crystal structures of the utp-bound and apo forms of the minimal trypanosomal tutase, tbtut4, which is composed solely of the n-terminal catalytic and c-terminal base-recognition domain ... | 2007 | 17785418 |
| a glycosylphosphatidylinositol-based treatment alleviates trypanosomiasis-associated immunopathology. | the gpi-anchored trypanosome variant surface glycoprotein (vsg) triggers macrophages to produce tnf, involved in trypanosomiasis-associated inflammation and the clinical manifestation of sleeping sickness. aiming at inhibiting immunopathology during experimental trypanosoma brucei infections, a vsg-derived gpi-based treatment approach was developed. to achieve this, mice were exposed to the gpi before an infectious trypanosome challenge. this gpi-based strategy resulted in a significant prolonge ... | 2007 | 17785839 |
| dihydroxyacetone induced autophagy in african trypanosomes. | dihydroxyacetone (dha) was examined to explore its trypanocidal activity. the compound is easily taken up by trypanosomes via its aquaglyceroporins but is not converted to a glycolytic intermediate due to the lack of a respective kinase. investigating the dha-induced cell death it became evident that parasites die by autophagy rather than by necrosis or apoptosis. since autophagy is not well studied in african trypanosomes our work offers a way to investigate the importance of autophagy for tryp ... | 2007 | 17786028 |
| structural flexibility in trypanosoma brucei enolase revealed by x-ray crystallography and molecular dynamics. | enolase is a validated drug target in trypanosoma brucei. to better characterize its properties and guide drug design efforts, we have determined six new crystal structures of the enzyme, in various ligation states and conformations, and have carried out complementary molecular dynamics simulations. the results show a striking structural diversity of loops near the catalytic site, for which variation can be interpreted as distinct modes of conformational variability that are explored during the ... | 2007 | 17822439 |
| the argonaute protein tbago1 contributes to large and mini-chromosome segregation and is required for control of rime retroposons and rhs pseudogene-associated transcripts. | the protist trypanosoma brucei possesses a single argonaute gene called tbago1 that is necessary for rnai silencing. we previously showed that in strain 427, tbago1 knock-out leads to a slow growth phenotype and to chromosome segregation defects. here we report that the slow growth phenotype is linked to defects in segregation of both large and mini-chromosome populations, with large chromosomes being the most affected. these phenotypes are completely reversed upon inducible re-expression of tba ... | 2007 | 17822785 |
| hemoglobin is a co-factor of human trypanosome lytic factor. | trypanosome lytic factor (tlf) is a high-density lipoprotein (hdl) subclass providing innate protection to humans against infection by the protozoan parasite trypanosoma brucei brucei. two primate-specific plasma proteins, haptoglobin-related protein (hpr) and apolipoprotein l-1 (apol-1), have been proposed to kill t. b. brucei both singularly or when co-assembled into the same hdl. to better understand the mechanism of t. b. brucei killing by tlf, the protein composition of tlf was investigated ... | 2007 | 17845074 |
| elongation factor 1a mediates the specificity of mitochondrial trna import in t. brucei. | mitochondrial trna import is widespread in eukaryotes. yet, the mechanism that determines its specificity is unknown. previous in vivo experiments using the trnas(met), trna(ile) and trna(lys) have suggested that the t-stem nucleotide pair 51:63 is the main localization determinant of trnas in trypanosoma brucei. in the cytosol-specific initiator trna(met), this nucleotide pair is identical to the main antideterminant that prevents interaction with cytosolic elongation factor (eef1a). here we sh ... | 2007 | 17853889 |
| dileucine signal-dependent and ap-1-independent targeting of a lysosomal glycoprotein in trypanosoma brucei. | sorting of trans-membrane proteins destined for the lysosome is achieved by selective inclusion into post-golgi transport vesicles. in higher eukaryotes sorting may be mediated by a peptidic motif, principally acidic clusters and tyrosine- or dileucine-based cytoplasmic signals or by inclusion of mannose-6-phosphate (m6p) into the n-glycans of lysosomal proteins. in african trypanosomes a major lysosomal trans-membrane protein is cb-1/p67. the cytoplasmic domain of p67 lacks tyrosine and lysine, ... | 2007 | 17869353 |
| telomere length in trypanosoma brucei. | trypanosoma brucei thwarts the host immune response by replacing its variant surface glycoprotein (vsg). the actively transcribed vsg is located in one of approximately 20 telomeric expression sites (es). antigenic variation can occur by transcriptional switching, reciprocal translocations, or duplicative gene conversion events among es or with the large repertoire of telomeric and non-telomeric vsg. in recently isolated strains, duplicative gene conversion occurs at a high frequency and predomi ... | 2008 | 17910953 |
| assessment of the phytochemical and antitrypanosomal properties of some extracts of leaves, stem and root bark of landolphia sp., p. beauv. | introduction/justification: there is urgent need to source for alternative chemotherapy against trypanosmosis, a disease of major importance in human and economic animals. | 2007 | 17913413 |
| differentiation of 1-o-alk-1'-enyl-2-acyl and 1-o-alkyl-2-acyl glycerophospholipids by multiple-stage linear ion-trap mass spectrometry with electrospray ionization. | we described linear ion-trap mass spectrometric approaches applying ms(3) and ms(4) toward to the structural characterization of 1-o-alk-1'-enyl-2-acyl-, 1-o-alkyl-2-acyl-, and diacyl-glycerophospholipids (gpl) as the [m - h](-) ions desorbed by esi in negative-ion mode. further dissociation of the [lm - h - r(2)co(2)h - polar head group](-) ions from the [m - h](-) ions of gpl that have undergone the consecutive losses of the fatty acid substituent at sn-2 and the polar head group readily gives ... | 2007 | 17913512 |
| validation of spermidine synthase as a drug target in african trypanosomes. | the trypanocidal activity of the odc (ornithine decarboxylase) inhibitor dfmo (difluoromethylornithine) has validated polyamine biosynthesis as a target for chemotherapy. as dfmo is one of only two drugs used to treat patients with late-stage african trypanosomiasis, the requirement for additional drug targets is paramount. here, we report the biochemical properties of tbspsyn (trypanosoma brucei spermidine synthase), the enzyme immediately downstream of odc in this pathway. recombinant tbspsyn ... | 2008 | 17916066 |
| c to u editing at position 32 of the anticodon loop precedes trna 5' leader removal in trypanosomatids. | in all organisms, precursor trnas are processed into mature functional units by post-transcriptional changes. these involve 5' and 3' end trimming as well as the addition of a significant number of chemical modifications, including rna editing. the only known example of non-organellar c to u editing of trnas occurs in trypanosomatids. in this system, editing at position 32 of the anticodon loop of trna(thr)(agu) stimulates, but is not required for, the subsequent formation of inosine at position ... | 2007 | 17916576 |
| the f-box protein cfb2 is required for cytokinesis of bloodstream-form trypanosoma brucei. | f-box proteins serve as mediators in targeting bound target proteins for ubiquitination and destruction. we here describe the roles of two f-box proteins, cfb1 and cfb2, in the trypanosome cell cycle. five almost identical copies of cfb1 are arranged in a direct tandem repeat on trypanosoma brucei chromosome 1; immediately downstream is a single cfb2 gene. rnai targeting cfb1 in bloodstream-form trypanosomes had a transient effect on growth and mitosis. depletion of cfb2, in contrast, resulted i ... | 2007 | 17920137 |
| effects of trypanosoma brucei tryptophanyl-trna synthetases silencing by rna interference. | the kinetoplast genetic code deviates from the universal code in that 90% of mitochondrial tryptophans are specified by uga instead of ugg codons. a single nucleus-encoded trna trp(cca) is used by both nuclear and mitochondria genes, since all kinetoplast trnas are imported into the mitochondria from the cytoplasm. to allow decoding of the mitochondrial uga codons as tryptophan, the trna trp(cca) anticodon is changed to uca by an editing event. two tryptophanyl trna synthetases (trprss) have bee ... | 2007 | 17924007 |
| trypanosome mtr4 is involved in rrna processing. | the yeast putative rna helicase mtr4p is implicated in exosome-mediated rna quality control in the nucleus, interacts with the exosome, and is found in the 'tramp' complex with a yeast nuclear poly(a) polymerase (trf4p/pap2p or trf5p) and a putative rna-binding protein, air1p or air2p. depletion of the trypanosoma brucei mtr4-like protein tbmtr4 caused growth arrest and defects in 5.8s rrna processing similar to those seen after depletion of the exosome. tbnpapl, a nuclear protein which is a put ... | 2007 | 17940093 |
| a repetitive protein essential for the flagellum attachment zone filament structure and function in trypanosoma brucei. | the flagellum is attached along the length of the cell body in the protozoan parasite trypanosoma brucei and is a defining morphological feature of this parasite. the flagellum attachment zone (faz) is a complex structure and has been characterised morphologically as comprising a faz filament structure and the specialised microtubule quartet (mtq) plus the specialised areas of flagellum: plasma membrane attachment. unfortunately, we have no information as to the molecular identity of the faz fil ... | 2008 | 17945531 |
| evidence for a capping enzyme with specificity for the trypanosome spliced leader rna. | capping of the pre-mrna 5' end by addition a monomethylated guanosine cap (m(7)g) is an essential and the earliest modification in the biogenesis of mrna. the reaction is catalyzed by three enzymes: triphosphatase, guanylyltransferase, and (guanine n-7) methyltransferase. whereas this modification occurs co-transcriptionally in most eukaryotic organisms, trypanosomatid protozoa mrnas acquire the m(7)g cap by trans-splicing, which entails the transfer of the capped spliced leader (sl) from the sl ... | 2007 | 17949828 |
| novel trypanocidal analogs of 5'-(methylthio)-adenosine. | the purine nucleoside 5'-deoxy-5'-(hydroxyethylthio)-adenosine (heta) is an analog of the polyamine pathway metabolite 5'-deoxy-5'-(methylthio)-adenosine (mta). heta is a lead structure for the ongoing development of selectively targeted trypanocidal agents. thirteen novel heta analogs were synthesized and examined for their in vitro trypanocidal activities against bloodstream forms of trypanosoma brucei brucei lab 110 eatro and at least one drug-resistant trypanosoma brucei rhodesiense clinical ... | 2008 | 17954686 |
| interleukin-12p70-dependent interferon- gamma production is crucial for resistance in african trypanosomiasis. | african trypanosomiasis encompasses diseases caused by pathogenic trypanosomes, infecting both humans and animals. in the present article, we dissected the possible role of members of the interleukin (il)-12 family during infection with trypanosoma brucei brucei and trypanosoma evansi in mice. il-12p35(-/-), il-12p40(-/-), and il-12p35(-/-)/p40(-/-) mice were susceptible to both pathogens, as was demonstrated by the increased mortality among these mice, compared with wild-type c57bl/6 mice. the ... | 2007 | 17955445 |
| activity of sulfonium bisphosphonates on tumor cell lines. | we investigated three series of sulfonium bisphosphonates for their activity in inhibiting the growth of three human tumor cell lines. the first series consisted of 6 cyclic sulfonium bisphosphonates, the most active species having an (average) ic50 of 89 microm. the second consisted of 10 phenylalkyl and phenylalkoxy bisphosphonates, the most active species having an ic50 of 18 microm. the third series consisted of 17 n-alkyl sulfonium bisphosphonates, the most active species having an ic50 of ... | 2007 | 17963374 |
| a novel, high-throughput technique for species identification reveals a new species of tsetse-transmitted trypanosome related to the trypanosoma brucei subgenus, trypanozoon. | we describe a novel method of species identification, fluorescent fragment length barcoding, based on length variation in regions of the 18s and 28salpha ribosomal dna. fluorescently tagged primers, designed in conserved regions of the 18s and 28salpha ribosomal dna, were used to amplify fragments with inter-species size variation, and sizes determined accurately using an automated dna sequencer. by using multiple regions and different fluorochromes, a barcode unique to each species was generate ... | 2008 | 17964224 |
| identification of new kinetoplast dna replication proteins in trypanosomatids based on predicted s-phase expression and mitochondrial targeting. | trypanosomatid parasites contain an unusual form of mitochondrial dna (kinetoplast dna [kdna]) consisting of a catenated network of several thousand minicircles and a smaller number of maxicircles. many of the proteins involved in the replication and division of kdna are likely to have no counterparts in other organisms and would not be identified by similarity to known replication proteins in other organisms. a new kdna replication protein conserved in kinetoplastids has been identified based o ... | 2007 | 17965251 |
| synthesis, characterisation and anti-protozoal activity of carbamate-derived polyazamacrocycles. | a short, highly efficient approach for the synthesis of a novel class of polyazamacrocycles containing n-functionalised carbamate side-chains has been developed. the key steps involved a phase-transfer mediated macrocyclisation to form the ring system as well as a tin-catalysed reaction with isocyanates to introduce the carbamate side-chains. x-ray crystallography confirmed successful formation of the 1,4,7,10-tetraazacyclododecane ring and n-functionalisation of all the amine centres. prelimina ... | 2007 | 17971994 |
| multifunctional class i transcription in trypanosoma brucei depends on a novel protein complex. | the vector-borne, protistan parasite trypanosoma brucei is the only known eukaryote with a multifunctional rna polymerase i that, in addition to ribosomal genes, transcribes genes encoding the parasite's major cell-surface proteins-the variant surface glycoprotein (vsg) and procyclin. in the mammalian bloodstream, antigenic variation of the vsg coat is the parasite's means to evade the immune response, while procyclin is necessary for effective establishment of trypanosome infection in the fly. ... | 2007 | 17972917 |
| dipeptidyl-alpha,beta-epoxyesters as potent irreversible inhibitors of the cysteine proteases cruzain and rhodesain. | the dipeptidyl epoxyesters 3 and 4 are potent, irreversible inhibitors of cruzain and rhodesain. | 2007 | 17977725 |
| hydrodynamic flow-mediated protein sorting on the cell surface of trypanosomes. | the unicellular parasite trypanosoma brucei rapidly removes host-derived immunoglobulin (ig) from its cell surface, which is dominated by a single type of glycosylphosphatidylinositol-anchored variant surface glycoprotein (vsg). we have determined the mechanism of antibody clearance and found that ig-vsg immune complexes are passively sorted to the posterior cell pole, where they are endocytosed. the backward movement of immune complexes requires forward cellular motility but is independent of e ... | 2007 | 17981118 |
| the role of the mitochondrial glycine cleavage complex in the metabolism and virulence of the protozoan parasite leishmania major. | for the human pathogen leishmania major, a key metabolic function is the synthesis of thymidylate, which requires 5,10-methylenetetrahydrofolate (5,10-ch(2)-thf). 5,10-ch(2)-thf can be synthesized from glycine by the mitochondrial glycine cleavage complex (gcc). bioinformatic analysis revealed the four subunits of the gcc in the l. major genome, and the role of the gcc in parasite metabolism and virulence was assessed through studies of the p subunit (glycine decarboxylase (gcvp)). first, a tagg ... | 2008 | 17981801 |
| protozoadb: dynamic visualization and exploration of protozoan genomes. | protozoadb (http://www.biowebdb.org/protozoadb) is being developed to initially host both genomics and post-genomics data from plasmodium falciparum, entamoeba histolytica, trypanosoma brucei, t. cruzi and leishmania major, but will hopefully host other protozoan species as more genomes are sequenced. it is based on the genomics unified schema and offers a modern web-based interface for user-friendly data visualization and exploration. this database is not intended to duplicate other similar eff ... | 2008 | 17981844 |
| elucidating the role of c/d snorna in rrna processing and modification in trypanosoma brucei. | most eukaryotic c/d small nucleolar rnas (snornas) guide 2'-o methylation (nm) on rrna and are also involved in rrna processing. the four core proteins that bind c/d snorna in trypanosoma brucei are fibrillarin (nop1), nop56, nop58, and snu13. silencing of nop1 by rna interference identified rrna-processing and modification defects that caused lethality. systematic mapping of 2'-o-methyls on rrna revealed the existence of hypermethylation at certain positions of the rrna in the bloodstream form ... | 2008 | 17981991 |
| the chagas' disease parasite trypanosoma cruzi exploits nerve growth factor receptor trka to infect mammalian hosts. | trypanosoma cruzi, the agent of chagas' disease, is an obligate intracellular parasite that invades various organs including several cell types in the nervous system that express the trk receptor tyrosine kinase. activation of trk is a major cell-survival and repair mechanism, and parasites could use trks to invade cells as a strategy to protect their habitat and prolong parasitism of vertebrate hosts. we show that t. cruzi binds to trka specifically and activates trka-dependent survival mechani ... | 2007 | 18005706 |
| cre recombinase-based positive-negative selection systems for genetic manipulation in trypanosoma brucei. | the limited repertoire of drug-resistance markers imposes a serious obstacle to genetic manipulation of trypanosoma brucei. here we describe experiments with a fusion protein that allows positive selection for genome integration followed by cre recombinase-mediated excision of the marker cassette that can be selected by ganciclovir, although the excision event is so efficient that selection is not strictly necessary. we describe two variants of the tetracycline-inducible plew100-based cre-expres ... | 2008 | 18006158 |
| regulation of a transmembrane protein gene family by the small rna-binding proteins tbubp1 and tbubp2. | the loci tb927.3.4070, 927.3.4080, tb927.3.4090, 927.3.4100 and 927.3.4110 of trypanosoma brucei encode five similar proteins with 13-14 transmembrane domains. corresponding mrnas are more abundant in bloodstream-form trypanosomes than in procyclics. the 4070, 4090 and 4110 genes have almost identical 3'-intergenic regions and the predicted proteins share a short c-terminal extension; a reporter mrna with the 4110 3'-untranslated region was more abundant in bloodstream forms than procyclic forms ... | 2008 | 18022708 |
| novel membrane-bound eif2alpha kinase in the flagellar pocket of trypanosoma brucei. | translational control mediated by phosphorylation of the alpha subunit of the eukaryotic initiation factor 2 (eif2alpha) is central to stress-induced programs of gene expression. trypanosomatids, important human pathogens, display differentiation processes elicited by contact with the distinct physiological milieu found in their insect vectors and mammalian hosts, likely representing stress situations. trypanosoma brucei, the agent of african trypanosomiasis, encodes three potential eif2alpha ki ... | 2007 | 17873083 |
| small trypanosome rna-binding proteins tbubp1 and tbubp2 influence expression of f-box protein mrnas in bloodstream trypanosomes. | in the african trypanosome trypanosoma brucei nearly all control of gene expression is posttranscriptional; sequences in the 3'-untranslated regions of mrnas determine the steady-state mrna levels by regulation of rna turnover. here we investigate the roles of two related proteins, tbubp1 and tbubp2, containing a single rna recognition motif, in trypanosome gene expression. tbubp1 and tbubp2 are in the cytoplasm and nucleus, comprise ca. 0.1% of the total protein, and are not associated with pol ... | 2007 | 17873084 |
| trypanocidal and antileishmanial dihydrochelerythrine derivatives from garcinia lucida. | three benzo[ c]phenanthridine alkaloids have been isolated from the stem bark of garcinia lucida: dihydrochelerythrine ( 1), 6-acetonyldihydrochelerythrine ( 2), and its new derivative, ( s)1''-(9,10-dihydro-2',3'-dihydroxy-7,8-dimethoxy-10-methyl-1,2-benzophenanthridin-9-yl)propan-2''-one (lucidamine a) ( 3). the new diisoprenylated derivative of lucidamine b ( 4) was obtained by semisynthesis. these dihydrochelerythrine derivatives as well as the crude extract displayed attractive antiprotozoa ... | 2007 | 17880175 |
| activation of endocytosis as an adaptation to the mammalian host by trypanosomes. | immune evasion in african trypanosomes is principally mediated by antigenic variation, but rapid internalization of surface-bound immune factors may contribute to survival. endocytosis is upregulated approximately 10-fold in bloodstream compared to procyclic forms, and surface coat remodeling accompanies transition between these life stages. here we examined expression of endocytosis markers in tsetse fly stages in vivo and monitored modulation during transition from bloodstream to procyclic for ... | 2007 | 17905918 |
| members of a large retroposon family are determinants of post-transcriptional gene expression in leishmania. | trypanosomatids are unicellular protists that include the human pathogens leishmania spp. (leishmaniasis), trypanosoma brucei (sleeping sickness), and trypanosoma cruzi (chagas disease). analysis of their recently completed genomes confirmed the presence of non-long-terminal repeat retrotransposons, also called retroposons. using the 79-bp signature sequence common to all trypanosomatid retroposons as bait, we identified in the leishmania major genome two new large families of small elements--lm ... | 2007 | 17907803 |
| human serum lyses trypanosoma brucei by triggering uncontrolled swelling of the parasite lysosome. | trypanosoma brucei brucei infects a wide range of mammals, but is unable to infect humans because this subspecies is lysed by normal human serum (nhs). the phenotype of cellular lysis is debated. for some authors the lysosome undergoes osmotic swelling due to massive influx of chloride ions from the cytoplasmic compartment, but others describe multiple small cytoplasmic vacuoles and general swelling of the cellular body. using population-level imaging of live immobilized trypanosomes throughout ... | 2007 | 17910690 |
| trypanocidal activity of piperazine-linked bisbenzamidines and bisbenzamidoxime, an orally active prodrug. | a series of 32 piperazine-linked bisbenzamidines (and related analogues) were analysed for their in vitro and in vivo trypanocidal activity against a drug-sensitive strain of trypanosoma brucei brucei and a drug-resistant strain of trypanosoma brucei rhodesiense. the compounds showed similar potencies against both strains. the most potent compounds were bisbenzamidines substituted at the amidinium nitrogens with a linear pentyl group (8, inhibitory concentration for 50% (ic(50))=1.7-3.0 nm) or c ... | 2007 | 17920820 |
| trypanosoma brucei rna binding proteins p34 and p37 mediate nopp44/46 cellular localization via the exportin 1 nuclear export pathway. | we have previously identified and characterized two novel nuclear rna binding proteins, p34 and p37, which have been shown to interact with a family of nucleolar phosphoproteins, nopp44/46, in trypanosoma brucei. these proteins are nearly identical, the major difference being an 18-amino-acid insert in the n terminus of p37. in order to characterize the interaction between p34 and p37 and nopp44/46, we have utilized an rna interference (rnai) cell line that specifically targets p34 and p37. with ... | 2007 | 17921352 |
| asymmetric cell division as a route to reduction in cell length and change in cell morphology in trypanosomes. | african trypanosomes go through at least five developmental stages during their life cycle. the different cellular forms are classified using morphology, including the order of the nucleus, flagellum and kinetoplast along the anterior-posterior axis of the cell, the predominant cell surface molecules and the location within the host. here, an asymmetrical cell division cycle that is an integral part of the trypanosoma brucei life cycle has been characterised in further detail through the use of ... | 2008 | 17931969 |
| tousled-like kinase in a microbial eukaryote regulates spindle assembly and s-phase progression by interacting with aurora kinase and chromatin assembly factors. | the tousled-like kinases are an evolutionarily conserved family of proteins implicated in dna repair, dna replication and mitosis in metazoans and plants. their absence from the yeasts and other eukaryotic 'microbes' suggests a specific role for them in the development of multicellular organisms. in this study, two closely related tousled-like kinase homologs, tlk1 and tlk2, were identified in trypanosoma brucei, a unicellular protozoan parasite. only tlk1 plays an essential role in cell growth, ... | 2007 | 17940067 |
| role of the trypanosoma brucei natural cysteine peptidase inhibitor icp in differentiation and virulence. | icp is a chagasin-family natural tight binding inhibitor of clan ca, family c1 cysteine peptidases (cps). we investigated the role of icp in trypanosoma brucei by generating bloodstream form icp-deficient mutants (deltaicp). a threefold increase in cp activity was detected in lysates of deltaicp, which was restored to the levels in wild type parasites by re-expression of the gene in the null mutant. deltaicp displayed slower growth in culture and increased resistance to a trypanocidal synthetic ... | 2007 | 17944830 |
| wcb is a c2 domain protein defining the plasma membrane - sub-pellicular microtubule corset of kinetoplastid parasites. | wcb is a protein that locates between the inner face of the plasma membrane and the sub-pellicular corset of microtubules in trypanosoma brucei. we provide the molecular identity of wcb and bioinformatic analysis suggests that it possesses a c2 domain implicated in membrane/protein interactions and a highly charged region possessing characteristics of a putative tubulin-binding domain. functional analyses via rna interference (rnai) depletion show that wcb is essential for cell morphogenesis. de ... | 2008 | 17951107 |
| a function for a specific zinc metalloprotease of african trypanosomes. | the trypanosoma brucei genome encodes three groups of zinc metalloproteases, each of which contains approximately 30% amino acid identity with the major surface protease (msp, also called gp63) of leishmania. one of these proteases, tbmsp-b, is encoded by four nearly identical, tandem genes transcribed in both bloodstream and procyclic trypanosomes. earlier work showed that rna interference against tbmsp-b prevents release of a recombinant variant surface glycoprotein (vsg) from procyclic trypan ... | 2007 | 17953481 |
| rna editing in trypanosoma brucei requires three different editosomes. | trypanosoma brucei has three distinct approximately 20s editosomes that catalyze rna editing by the insertion and deletion of uridylates. editosomes with the kren1 or kren2 rnase iii type endonucleases specifically cleave deletion and insertion editing site substrates, respectively. we report here that editosomes with krepb2, which also has an rnase iii motif, specifically cleave cytochrome oxidase ii (coii) pre-mrna insertion editing site substrates in vitro. conditional repression and mutation ... | 2008 | 17954557 |
| control and regulation of gene expression: quantitative analysis of the expression of phosphoglycerate kinase in bloodstream form trypanosoma brucei. | isoenzymes of phosphoglycerate kinase in trypanosoma brucei are differentially expressed in its two main life stages. this study addresses how the organism manages to make sufficient amounts of the isoenzyme with the correct localization, which processes (transcription, splicing, and rna degradation) control the levels of mrnas, and how the organism regulates the switch in isoform expression. for this, we combined new quantitative measurements of phosphoglycerate kinase mrna abundance, rna precu ... | 2008 | 17991737 |
| residues in an atp binding domain influence sugar binding in a trypanosome hexokinase. | trypanosoma brucei harbors two hexokinases (tbhk1 and tbhk2) that are 98% identical at the amino acid level. we previously found that recombinant tbhk1 (rtbhk1) has hexokinase activity, while rtbhk2 has not, a finding attributed to differences in the c-termini of the proteins. sequence analysis suggests that the c-termini of tbhks are part of a newly identified conserved motif found in other eukaryotic hexokinases. here, we have explored the role of tail residues in the differences in catalytic ... | 2008 | 17996732 |
| regulation of an amino acid transporter mrna in trypanosoma brucei. | trypanosoma brucei regulates gene expression by post-transcriptional mechanisms, such as mrna turnover and translation control. this regulation frequently requires specific sequences located in the 3'-untranslated region. microarray analysis and northern blot hybridization showed that the amino acid transporter 11 mrna is up-regulated in insect stages of the parasite. by rt-pcr and sequencing, the aatp11 polyadenylation site was mapped. we show that this 3'-utr causes higher expression of the ch ... | 2008 | 17996963 |
| the cell biology of trypanosoma brucei differentiation. | developmental events in the life-cycle of the sleeping sickness parasite comprise integrated changes in cell morphology, metabolism, gene expression and signalling pathways. in each case these processes differ from the eukaryotic norm. in the past three years, understanding of these developmental processes has progressed from a description of the cytological events of differentiation to a discovery of its underlying molecular controls. with an expanding set of reagents for the identification of ... | 2007 | 17997129 |
| structure of a glycosylphosphatidylinositol-anchored domain from a trypanosome variant surface glycoprotein. | the cell surface of african trypanosomes is covered by a densely packed monolayer of a single protein, the variant surface glycoprotein (vsg). the vsg protects the trypanosome cell surface from effector molecules of the host immune system and is the mediator of antigenic variation. the sequence divergence between vsgs that is necessary for antigenic variation can only occur within the constraints imposed by the structural features necessary to form the monolayer barrier. here, the structures of ... | 2008 | 18003615 |
| metacaspase 2 of trypanosoma brucei is a calcium-dependent cysteine peptidase active without processing. | metacaspases are cysteine peptidases that are distantly related to the caspases, for which proteolytic processing is central to their activation. here, we show that recombinant metacaspase 2 (mca2) from trypanosoma brucei has arginine/lysine-specific, ca(2+)-dependent proteolytic activity. autocatalytic processing of mca2 occurred after lys55 and lys268; however, this was shown not to be required for the enzyme to be proteolytically active. the necessity of ca(2+), but not processing, for mca2 e ... | 2007 | 18005666 |
| thermodynamic characterization of substrate and inhibitor binding to trypanosoma brucei 6-phosphogluconate dehydrogenase. | 6-phosphogluconate dehydrogenase is a potential target for new drugs against african trypanosomiasis. phosphorylated aldonic acids are strong inhibitors of 6-phosphogluconate dehydrogenase, and 4-phospho-d-erythronate (4pe) and 4-phospho-d-erythronohydroxamate are two of the strongest inhibitors of the trypanosoma brucei enzyme. binding of the substrate 6-phospho-d-gluconate (6pg), the inhibitors 5-phospho-d-ribonate (5pr) and 4pe, and the coenzymes nadp, nadph and nadp analogue 3-amino-pyridine ... | 2007 | 18021252 |
| trypanosoma brucei: differential requirement of membrane potential for import of proteins into mitochondria in two developmental stages. | trypanosome alternative oxidase (tao) and the cytochrome oxidase (cox) are two developmentally regulated terminal oxidases of the mitochondrial electron transport chain in trypanosoma brucei. here, we have compared the import of tao and cytochrome oxidase subunit iv (coiv), two stage-specific nuclear encoded mitochondrial proteins, into the bloodstream and procyclic form mitochondria of t. brucei to understand the import processes in two different developmental stages. under in vitro conditions ... | 2008 | 18021773 |
| sterol 14alpha-demethylase as a potential target for antitrypanosomal therapy: enzyme inhibition and parasite cell growth. | sterol 14alpha-demethylases (cyp51) serve as primary targets for antifungal drugs, and specific inhibition of cyp51s in protozoan parasites trypanosoma brucei (tb) and trypanosoma cruzi (tc) might provide an effective treatment strategy for human trypanosomiases. primary inhibitor selection is based initially on the cytochrome p450 spectral response to ligand binding. ligands that demonstrate strongest binding parameters were examined as inhibitors of reconstituted tb and tc cyp51 activity in vi ... | 2007 | 18022567 |
| cytokinesis in trypanosomatids. | the process of cytokinesis, where the cytoplasm of one cell is divided to produce two daughter cells, is intricate in trypanosomatids because of the requirement to replicate and segregate a number of single copy organelles, including the nucleus, kinetoplast, golgi apparatus, and flagellum. identifying regulators of the three stages of cytokinesis, initiation, furrow ingression, and abscission is complicated by the fact that cell division in trypanosomatids is easily perturbed and aberrant cells ... | 2007 | 18023244 |
| roles for tbdss-1 in rna surveillance and decay of maturation by-products from the 12s rrna locus. | the trypanosoma brucei exoribonuclease, tbdss-1, has been implicated in multiple aspects of mitochondrial rna metabolism. here, we investigate the role of tbdss-1 in rna processing and surveillance by analyzing 12s rrna processing intermediates in tbdss-1 rnai cells. rna fragments corresponding to leader sequence upstream of 12s rrna accumulate upon tbdss-1 depletion. the 5' extremity of 12s rrna is generated by endonucleolytic cleavage, and tbdss-1 degrades resulting upstream maturation by-prod ... | 2008 | 18032430 |
| the gup1 homologue of trypanosoma brucei is a gpi glycosylphosphatidylinositol remodelase. | glycosylphosphatidylinositol (gpi) lipids of trypanosoma brucei undergo lipid remodelling, whereby longer fatty acids on the glycerol are replaced by myristate (c14:0). a similar process occurs on gpi proteins of saccharomyces cerevisiae where per1p first deacylates, gup1p subsequently reacylates the anchor lipid, thus replacing a shorter fatty acid by c26:0. heterologous expression of the gup1 homologue of t. brucei in gup1delta yeast cells partially normalizes the gup1delta phenotype and resto ... | 2008 | 18036137 |
| evolutionary consequences of a large duplication event in trypanosoma brucei: chromosomes 4 and 8 are partial duplicons. | gene order along the genome sequence of the human parasite trypanosoma brucei provides evidence for a 0.5 mb duplication, comprising the 3' regions of chromosomes 4 and 8. here, the principal aim was to examine the contribution made by this duplication event to the t. brucei genome sequence, emphasising the consequences for gene content and the evolutionary change subsequently experienced by paralogous gene copies. the duplicated region may be browsed online at http://www.genedb.org/genedb/tryp/ ... | 2007 | 18036214 |
| kinetic and mutational analysis of the trypanosoma brucei nbt1 nucleobase transporter expressed in saccharomyces cerevisiae reveals structural similarities between ent and mfs transporters. | parasitic protozoa are unable to synthesise purines de novo and thus depend on the uptake of nucleosides and nucleobases across their plasma membrane through specific transporters. a number of nucleoside and nucleobase transporters from trypanosoma brucei brucei and leishmania major have recently been characterised and shown to belong to the equilibrative nucleoside transporter (ent) family. a number of studies have demonstrated the functional importance of particular transmembrane segments (tms ... | 2008 | 18036529 |
| comparative codon and amino acid composition analysis of tritryps-conspicuous features of leishmania major. | comparative analyses of codon/amino acid usage in leishmania major, trypanosoma brucei and trypanosoma cruzi reveal that gene expressivity and gc-bias play key roles in shaping the gene composition of all three parasites, and protein composition of l. major only. in t. brucei and t. cruzi, the major contributors to the variation in protein composition are hydropathy and/or aromaticity. principle of cost minimization is followed by t. brucei, disregarded by t. cruzi and opposed by l. major. slowl ... | 2007 | 18037385 |
| the tritryp phosphatome: analysis of the protein phosphatase catalytic domains. | the genomes of the three parasitic protozoa trypanosoma cruzi, trypanosoma brucei and leishmania major are the main subject of this study. these parasites are responsible for devastating human diseases known as chagas disease, african sleeping sickness and cutaneous leishmaniasis, respectively, that affect millions of people in the developing world. the prevalence of these neglected diseases results from a combination of poverty, inadequate prevention and difficult treatment. protein phosphoryla ... | 2007 | 18039372 |
| a monoclonal antibody that inhibits trypanosoma cruzi growth in vitro and its reaction with intracellular triosephosphate isomerase. | in parasites of the order kinetoplastida, such as trypanosoma cruzi and trypanosoma brucei, glycolysis is carried out by glycolytic enzymes in glycosomes. one of the glycolytic enzymes is triosephosphate isomerase (tim), which in t. brucei is localized exclusively in glycosomes, whereas in t. cruzi, the localization of tim has not been fully ascertained. in the present work, we made a monoclonal antibody (mab 6-11g) against recombinant t. cruzi tim (rtctim). incubation of t. cruzi epimastigotes ... | 2008 | 18046577 |
| mitochondrial origin-binding protein umsbp mediates dna replication and segregation in trypanosomes. | kinetoplast dna (kdna) is the remarkable mitochondrial genome of trypanosomatids. its major components are several thousands of topologically linked dna minicircles, whose replication origins are bound by the universal minicircle sequence-binding protein (umsbp). the cellular function of umsbp has been studied in trypanosoma brucei by using rnai analysis. silencing of the trypanosomal umsbp genes resulted in remarkable effects on the trypanosome cell cycle. it significantly inhibited the initiat ... | 2007 | 18048338 |
| the tbmtr1 spliced leader rna cap 1 2'-o-ribose methyltransferase from trypanosoma brucei acts with substrate specificity. | in metazoa cap 1 (m(7)gpppnmp-rna) is linked to higher levels of translation; however, the enzyme responsible remains unidentified. we have validated the first eukaryotic encoded cap 1 2'-o-ribose methyltransferase, tbmtr1, a member of a conserved family that modifies the first transcribed nucleotide of spliced leader and u1 small nuclear rnas in the kinetoplastid protozoan trypanosoma brucei. in addition to cap 0 (m(7)gpppnp-rna), mrna in these parasites has ribose methylations on the first fou ... | 2008 | 18048356 |
| p166, a link between the trypanosome mitochondrial dna and flagellum, mediates genome segregation. | kinetoplast dna (kdna), the trypanosome mitochondrial genome, is a giant network containing several thousand interlocked dna rings. within the mitochondrion, kdna is condensed into a disk-shaped structure positioned near the flagellar basal body. the disk is linked to the basal body by a remarkable transmembrane filament system named the tripartite attachment complex (tac). following kdna replication, the tac mediates network segregation, pulling the progeny networks into the daughter cells by t ... | 2008 | 18059470 |
| loss of actin does not affect export of newly synthesized proteins to the surface of trypanosoma brucei. | vesicle traffic to and from the surface is highly polarized in african trypanosomes. actin is required for polarized endocytic traffic in bloodstream forms of african trypanosomes but its role in other pathways has remained equivocal. a combination of metabolic pulse chase labelling and surface biotinylation during the chase period along with the use of conditional rna interference was employed to demonstrate that substantial loss of actin had no effect on the export of newly synthesized protein ... | 2008 | 18061288 |
| krepa6 is an rna-binding protein essential for editosome integrity and survival of trypanosoma brucei. | most mitochondrial mrnas in kinetoplastid protozoa require post-transcriptional rna editing that inserts and deletes uridylates, a process that is catalyzed by multiprotein editosomes. krepa6 is the smallest of six editosome proteins that have predicted oligonucleotide-binding (ob) folds. inactivation of krepa6 expression results in disruption and ultimate loss of approximately 20s editosomes and inhibition of procyclic form cell growth. gel shift studies show that recombinant krepa6 binds rna, ... | 2008 | 18065716 |
| genomic rearrangements and transcriptional analysis of the spliced leader-associated retrotransposon in rna interference-deficient trypanosoma brucei. | the trypanosoma brucei genome is colonized by the site-specific non-ltr retrotransposon slacs, or spliced leader-associated conserved sequence, which integrates exclusively into the spliced leader (sl) rna genes. although there is evidence that the rna interference (rnai) machinery regulates slacs transcript levels, we do not know whether rnai deficiency affects the genomic stability of slacs, nor do we understand the mechanism of slacs transcription. here, we report that prolonged culturing of ... | 2008 | 18067542 |
| antiprotozoal and cytotoxic screening of 45 plant extracts from democratic republic of congo. | to evaluate in vitro the antiprotozoal and cytotoxic activities of 80% methanol extract from 45 medicinal plants collected in sankuru (democratic republic of congo) against trypanosoma brucei brucei, trypanosoma cruzi and the chloroquine-sensitive ghanaian strain of plasmodium falciparum, and mrc-5 cell lines respectively. | 2008 | 18068320 |