Evidence for Guanosine Triphosphate—Binding Proteins in Trypanosoma cruzi

Hs, Oz; Huang, Huan; Wittner, Murray; Hb, Tanowitz; Jp, Bilezikian; Sa, Morris

doi:10.4269/ajtmh.1994.50.620

Cited by 18 publications

(5 citation statements)

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“…For example, G‐proteins have been implicated in the de‐flagellation response of Chlamydomonas reinhardtii (Quarmby et al 1992; Quarmby and Hartzell 1994). Additionally, G‐proteins have been identified by immunoblotting in Toxoplasma gondii (Halonen et al 1996), and by immunoblotting and ADP ribosylation in the flagellates Trypanosoma brucei (Coulter and Hide 1995), and Trypanosoma cruzi (Coso et al 1992; Oz et al 1994), where they may be involved in endocytosis, and regulation of the parasitic life cycle. Additionally, G‐proteins play an important role in chemotaxis of Dictyostelium amoebae (Parent and Devreotes 1999; Pupillo et al 1989).…”

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confidence: 99%

Partial Cloning of Putative G‐Proteins Modulating Mechanotransduction in the Ciliate Stentor

Marino

Sherman

Wood

2001

J Eukaryotic Microbiology

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Signal transduction systems known to utilize G-proteins in higher eukaryotes undoubtedly evolved prior to the development of metazoa. Pharmacological evidence indicates that the ciliates Paramecium, Stentor, and Tetrahymena all utilize signaling systems similar to those found in mammals. However, there has been relatively little direct evidence for the existence of G-proteins in ciliates. Since highly conserved heterotrimeric G-proteins form the basis of receptor-coupled signal transduction systems in a wide variety of metazoa, it is of interest to know if these important signaling molecules were early to evolve and are present and functionally important in a wide variety of unicellular organisms. We have previously shown that mechanotransduction in Stentor is modulated by opiates in a manner that may involve pertussis toxin-sensitive G-proteins. Here we utilize drugs known to interact with G-proteins to further test for the involvement of these important signaling molecules in Stentor mechanotransduction. We present behavioral and electrophysiological data demonstrating that putative G-proteins in Stentor decrease mechanical sensitivity by modulating the mechanotransduction process. In addition, we report the partial cloning of 4 G-protein alpha-subunits from Stentor. We confirm that these clones are of Stentor origin and are transcribed. Furthermore, we employ antisense oligodeoxynucleotide-mediated knockout to demonstrate that these ciliate G-proteins exert a modulatory influence on Stentor behavior, and that a G1/G0-like clone mediates the inhibitory action of beta-endorphin on mechanotransduction.

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confidence: 99%

Partial Cloning of Putative G‐Proteins Modulating Mechanotransduction in the Ciliate Stentor

Marino

Sherman

Wood

2001

J Eukaryotic Microbiology

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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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confidence: 99%

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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“…In fact, cyclic nucleotides seem to be essential for parasitic proliferation and differentiation. For example, since the nineties, life-stage specific functional elements of G-proteins have been demonstrated in Trypanosoma (brucei) brucei ( Coulter and Hide, 1995 ) as well as in Trypanosoma cruzi ( Oz et al., 1994 ), however, canonical G-proteins have not been still recognized and seem to be absent at least in the genome; bioinformatic analysis yields data for encoding GPCRs that seem to be without functional proof, and small GTPases or their secondary effector proteins with structural differences to host orthologues seem to constitute the molecular mean for the role cyclic nucleotides have ( Kaiser, 2019 ).…”

Section: G Protein Signaling Mechanisms In Trypanosomatidaementioning

confidence: 99%

G Protein-Coupled Receptors as Potential Intercellular Communication Mediators in Trypanosomatidae

Díaz

Febres

Giammarresi

et al. 2022

Front. Cell. Infect. Microbiol.

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Detection and transduction of environmental signals, constitute a prerequisite for successful parasite invasion; i.e., Leishmania transmission, survival, pathogenesis and disease manifestation and dissemination, with diverse molecules functioning as inter-cellular signaling ligands. Receptors [i.e., G protein-coupled receptors (GPCRs)] and their associated transduction mechanisms, well conserved through evolution, specialize in this function. However, canonical GPCR-related signal transduction systems have not been described in Leishmania, although orthologs, with reduced domains and function, have been identified in Trypanosomatidae. These inter-cellular communication means seem to be essential for multicellular and unicellular organism’s survival. GPCRs are flexible in their molecular architecture and may interact with the so-called receptor activity-modifying proteins (RAMPs), which modulate their function, changing GPCRs pharmacology, acting as chaperones and regulating signaling and/or trafficking in a receptor-dependent manner. In the skin, vasoactive- and neuro- peptides released in response to the noxious stimuli represented by the insect bite may trigger parasite physiological responses, for example, chemotaxis. For instance, in Leishmania (V.) braziliensis, sensory [Substance P, SP, chemoattractant] and autonomic [Vasoactive Intestinal Peptide, VIP, and Neuropeptide Y, NPY, chemorepellent] neuropeptides at physiological levels stimulate in vitro effects on parasite taxis. VIP and NPY chemotactic effects are impaired by their corresponding receptor antagonists, suggesting that the stimulated responses might be mediated by putative GPCRs (with essential conserved receptor domains); the effect of SP is blocked by [(D-Pro 2, D-Trp7,9]-Substance P (10-6 M)] suggesting that it might be mediated by neurokinin-1 transmembrane receptors. Additionally, vasoactive molecules like Calcitonin Gene-Related Peptide [CGRP] and Adrenomedullin [AM], exert a chemorepellent effect and increase the expression of a 24 kDa band recognized in western blot analysis by (human-)-RAMP-2 antibodies. In-silico search oriented towards GPCRs-like receptors and signaling cascades detected a RAMP-2-aligned sequence corresponding to Leishmania folylpolyglutamate synthase and a RAMP-3 aligned protein, a hypothetical Leishmania protein with yet unknown function, suggesting that in Leishmania, CGRP and AM activities may be modulated by RAMP- (-2) and (-3) homologs. The possible presence of proteins and molecules potentially involved in GPCRs cascades, i.e., RAMPs, signpost conservation of ancient signaling systems associated with responses, fundamental for cell survival, (i.e., taxis and migration) and may constitute an open field for description of pharmacophores against Leishmania parasites.

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Evidence for Guanosine Triphosphate—Binding Proteins in Trypanosoma cruzi

Cited by 18 publications

References 0 publications

Partial Cloning of Putative G‐Proteins Modulating Mechanotransduction in the Ciliate Stentor

Partial Cloning of Putative G‐Proteins Modulating Mechanotransduction in the Ciliate Stentor

Protein Farnesyltransferase from Trypanosoma brucei

G Protein-Coupled Receptors as Potential Intercellular Communication Mediators in Trypanosomatidae

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