Evidence for the existence of an Ns-type regulatory protein in <i>Trypanosoma cruzi</i> membranes

Eisenschlos, C; Paladini, Alejandro; Vedia, L Molina y; Torres, Héctor N.; Flawiá, Mirtha M.

doi:10.1042/bj2370913

Cited by 29 publications

(16 citation statements)

References 19 publications

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“…They serve as coupling units between membrane-bound receptors and effector units such as adenylate cyclase or phospholipase C. There are reports that G proteins, with characteristics similar to those of proteins known to participate in hormonally regulated signal transduction systems in higher eukaryotes, are present in T. cruzi (72). However, it has not been established that these G proteins participate in an identical manner in this parasite.…”

Section: Introductionmentioning

confidence: 99%

Chagas' disease

et al. 1992

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Chagas' disease, caused by Trypanosoma cruzi, is an important cause of morbidity in many countries in Latin America. The important modes of transmission are by the bite of the reduviid bug and blood transfusion. The organism exists in three morphological forms: trypomastigotes, amastigotes, and epimastigotes. The mechanism of transformation and differentiation is currently being explored, and signal transduction pathways of the parasites may be involved in this process. Parasite adherence to and invasion of host cells is a complex process involving complement, phospholipase, penetrin, neuraminidase, and hemolysin. Two clinical forms of the disease are recognized, acute and chronic. During the acute stage pathological damage is related to the presence of the parasite, whereas in the chronic stage few parasites are found. In recent years the roles of tumor necrosis factor, gamma interferon, and the interleukins in the pathogenesis of this infection have been reported. The common manifestations of chronic cardiomyopathy are arrhythmias and thromboembolic events. Autoimmune, neurogenic, and microvascular factors may be important in the pathogenesis of the cardiomyopathy. The gastrointestinal tract is another important target, and "mega syndromes" are common manifestations. The diagnosis and treatment of this infection are active areas of investigation. New serological and molecular biological techniques have improved the diagnosis of chronic infection. Exacerbations of T. cruzi infection have been reported for patients receiving immuno-suppressive therapy and for those with AIDS.

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Section: Introductionmentioning

confidence: 99%

Chagas' disease

et al. 1992

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“…In addition, metacyclic trypomastigotes exhibit higher intracellular cyclic AMP levels than epimastigotes (13), and evidence from this laboratory has shown that T. cruzi membranes possess an adenylyl cyclase associated with the a subunit of the stimulatory guanine nucleotide-binding regulatory protein (G protein) (14). Gai and Gf3 polypeptides were also found in these membranes (15).…”

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confidence: 99%

Stimulation of Trypanosoma cruzi adenylyl cyclase by an alpha D-globin fragment from Triatoma hindgut: effect on differentiation of epimastigote to trypomastigote forms.

Fraidenraich

Peña

Isola

et al. 1993

Proc. Natl. Acad. Sci. U.S.A.

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A peptide from hindguts of the Triatoma hematophagous Chagas insect vector activates adenylyl cyclase activity in Trypanosoma cruzi epimastigote membranes and stimulates the in vitro differentiation of epimatigotes to metacyclic trypomastigotes. Hindguts were obtained from insects fed 2 days earlier with chicken blood. Purification was performed by gel fDtration and HPLC on Cis and C4 columns. SDS/PAGE of the purified peptide showed a single band of about 10 kDa. The foilowing sequence was determined for the 20 amino-terminal residues of this peptide: H2N-Met-Leu-Thr-Ala-Glu-Asp-LysLys-Leu-lle-Gln-Gln-Ala-Trp-Glu-Lys-Ala-Ala-Ser-His. This sequence is identical to the amino terminus ofchicken aD-globin. On a Western blot, the peptide immunoreacted with a polyclonal antibody against chicken globin D. A synthetic peptide corresponding to residues 1-40 of the aD-globin amino terminus also stimulated adenylyl cyclase activity and promoted differentiation. This 125I-labeled synthetic peptide bound specificaily to T. cyui epimastiote cells. Activation of epimastigote adenylyl cyclase by the hemoglobin-derived peptide may play an important role in T. cru differentiation and consequently in the transmission of Chagas disease.A major endemia in Latin America is Chagas disease. Its etiological agent is Trypanosoma cruzi, a flagellate protozoan that undergoes complex morphological changes throughout its life cycle in both the insect vector and the vertebrate host (1, 2). The hematophagous Triatoma vector ingests circulating trypomastigote forms while feeding on the blood of an infected vertebrate host. In the insect digestive tract, ingested trypomastigotes initially differentiate to epimastigotes; in a second stage, which occurs within the vector hindgut, epimastigotes that are proliferative but not infectious convert to metacyclic trypomastigotes. The latter are infectious and nonproliferative parasite forms (3)(4)(5). This differentiation process, known as metacyclogenesis, can be induced in epimastigote liquid cultures by mammalian serum components (6), the use of medium mimicking insect urine (7), metabolic stress (8, 9), Triatoma infestans hindgut extracts (10, 11), or cyclic AMP (12).In addition, metacyclic trypomastigotes exhibit higher intracellular cyclic AMP levels than epimastigotes (13), and evidence from this laboratory has shown that T. cruzi membranes possess an adenylyl cyclase associated with the a subunit of the stimulatory guanine nucleotide-binding regu-

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“…The latter have been shown to be a major group of prenylated proteins in mammalian cells (6,39,40). Evidence is accumulating that Trypanosomatids contain heterotrimeric G proteins (41)(42)(43)(44)(45)(46)(47)(48), and the ␥-subunits of these signaling molecules are either geranylgeranylated (7,8) or farnesylated (49) in mammalian cells. Rab GTP-binding proteins, which are known to be doubly geranylgeranylated in mammalian cells, have recently been cloned from Trypanosomatids (50 -54).…”

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Protein Farnesyltransferase from Trypanosoma brucei

Yokoyama¹,

Trobridge²,

Buckner³

et al. 1998

Journal of Biological Chemistry

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We have previously shown that protein prenylation occurs in the Trypanosomatids Trypanosoma brucei (T. brucei), Trypanosoma cruzi, and Leishmania mexicana and that protein farnesyltransferase (PFT) activity can be detected in cytosolic extracts of insect (procyclic) form T. brucei. A PFT that transfers the farnesyl group from farnesyl pyrophosphate to a cysteine that is 4 residues upstream of the C terminus of the Ras GTP-binding protein RAS1-CVIM has now been purified 60,000-fold to near homogeneity from procyclic T. brucei. By screening a mixture of hexapeptides SSCALX (X is 20 different amino acids), it was found that SSCALM binds to T. brucei PFT with sub-micromolar affinity, and affinity chromatography using this peptide was a key step in the purification of this enzyme. On SDS-polyacrylamide gel electrophoresis, the enzyme migrates as a pair of bands with apparent molecular masses of 61 and 65 kDa, and thus its subunits are ϳ30% larger than those of the mammalian homolog. The 61-kDa band was identified as the putative ␤-subunit by photoaffinity labeling with a 32 P-labeled analog of farnesyl pyrophosphate. Mimetics of the C-terminal tetrapeptide of prenyl acceptors have been previously shown to inhibit mammalian PFT, and these compounds also inhibit T. brucei PFT with affinities in the nanomolar to micromolar range, although the structure-activity relationship is very different for parasite versus mammalian enzyme. Unlike mammalian cells, the growth of bloodstream T. brucei is completely inhibited by low micromolar concentrations of two of the PFT inhibitors, and these compounds also block protein farnesylation in cultured parasites. These compounds also potently block the growth of the intracellular (amastigote) form of T. cruzi grown in fibroblast host cells. The results suggest that protein farnesylation is a target for the development of anti-trypanosomatid chemotherapeutics.

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Evidence for the existence of an Ns-type regulatory protein in Trypanosoma cruzi membranes

Cited by 29 publications

References 19 publications

Chagas' disease

Chagas' disease

Stimulation of Trypanosoma cruzi adenylyl cyclase by an alpha D-globin fragment from Triatoma hindgut: effect on differentiation of epimastigote to trypomastigote forms.

Protein Farnesyltransferase from Trypanosoma brucei

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