Molecular Cloning and Characterization of a Protein Farnesyltransferase from the Enteric Protozoan Parasite Entamoeba histolytica

Abstract

Genes encoding α- and β-subunits of a putative protein farnesyltransferase (FT) from the enteric protozoan parasite Entamoeba histolytica were obtained and their biochemical properties were characterized. Deduced amino acid sequences of the α- and β-subunit of E. histolytica FT (EhFT) were 298- and 375-residues long with a molecular mass of 35.6 and 42.6 kDa, and a pI of 5.43 and 5.65, respectively. They showed 24% to 36% identity to and shared common signature domains and repeats with those from other organisms. Recombinant α- and β-subunits, co-expressed in Escherichia coli, formed a heterodimer and showed activity to transfer farnesyl using farnesylpyrophosphate as a donor to human H-Ras possessing a C-terminal CVLS, but not a mutant H-Ras possessing CVLL. Among a number of small GTPases that belong to the Ras superfamily from this parasite, we identified EhRas4, which possesses CVVA at the C terminus, as a sole farnesyl acceptor for EhFT. This is in contrast to mammalian FT, which utilizes a variety of small GTPases that possess a C-terminal CaaX motif, where X is serine, methionine, glutamine, cysteine, or alanine. EhFT also showed remarkable resistance against a variety of known inhibitors of mammalian FT. These results suggest that remarkable biochemical differences in binding to substrates and inhibitors exist between amebic and mammalian FTs, which highlights this enzyme as a novel target for the development of new chemotherapeutics against amebiasis. Genes encoding α- and β-subunits of a putative protein farnesyltransferase (FT) from the enteric protozoan parasite Entamoeba histolytica were obtained and their biochemical properties were characterized. Deduced amino acid sequences of the α- and β-subunit of E. histolytica FT (EhFT) were 298- and 375-residues long with a molecular mass of 35.6 and 42.6 kDa, and a pI of 5.43 and 5.65, respectively. They showed 24% to 36% identity to and shared common signature domains and repeats with those from other organisms. Recombinant α- and β-subunits, co-expressed in Escherichia coli, formed a heterodimer and showed activity to transfer farnesyl using farnesylpyrophosphate as a donor to human H-Ras possessing a C-terminal CVLS, but not a mutant H-Ras possessing CVLL. Among a number of small GTPases that belong to the Ras superfamily from this parasite, we identified EhRas4, which possesses CVVA at the C terminus, as a sole farnesyl acceptor for EhFT. This is in contrast to mammalian FT, which utilizes a variety of small GTPases that possess a C-terminal CaaX motif, where X is serine, methionine, glutamine, cysteine, or alanine. EhFT also showed remarkable resistance against a variety of known inhibitors of mammalian FT. These results suggest that remarkable biochemical differences in binding to substrates and inhibitors exist between amebic and mammalian FTs, which highlights this enzyme as a novel target for the development of new chemotherapeutics against amebiasis. Ras small GTPases function as a molecular switch of signal transduction in cell proliferation and differentiation (1.Boguski M.S. McCormick F. Nature. 1993; 366: 643-654Crossref PubMed Scopus (1762) Google Scholar). Ras small GTPases require a post-translational lipid modification called protein farnesylation in order to become membrane-associated and functional (2.Takai Y. Kaibuchi K. Kikuchi A. Kawata M. Int. Rev. Cytol. 1992; 133: 187-230Crossref PubMed Scopus (253) Google Scholar). Protein farnesylation, catalyzed by protein farnesyltransferase (FT) 1The abbreviations used are: FT, protein farnesyltransferase; GGT-I, protein geranylgeranyltrasferase type I; FTα, α-subunit of farnesyltransferase; FTβ, β-subunit of protein farnesyltransferase; EhFT, farnesyltransferase of E. histolytica; FPP, farnesyl pyrophosphate; NTA, nitrilotriacetic acid; GTPγS, guanosine 5′-3-O-(thio)triphosphate, NJ, neighbor-joining. (3.Zang F.L. Casey P.J. Annu. Rev. Biochem. 1996; 65: 241-269Crossref PubMed Scopus (1743) Google Scholar), which is comprised of two heterologous α- (FTα) and β- (FTβ) subunits, is a major post-translational lipid modification, together with protein geranylgeranylation (3.Zang F.L. Casey P.J. Annu. Rev. Biochem. 1996; 65: 241-269Crossref PubMed Scopus (1743) Google Scholar). FT and protein geranylgeranyltransferase type I (GGT-I) catalyze the transfer of the farnesyl and geranylgeranyl group from farnesyl pyrophosphate (FPP) and geranylgeranyl pyrophosphate, respectively, to the cysteine residue of a C-terminal CaaX of small GTPases including Ras, Rac, and Rho, where C is cysteine, a is usually an aliphatic amino acid, and X is any amino acid. Marked differences in substrate specificity have been shown between FT and GGT-I, i.e. FT mainly utilizes, as substrates, small GTPases possessing the terminal CaaX motif, when X is serine, methionine, glutamine, cysteine, or alanine (4.Moores S.L. Schaber M.D. Mosser S.D. Rands E. O'Hara M.B. Garsky V.M. Marshall M.S. Pompliano D.L. Gibbs J.B. J. Biol. Chem. 1991; 266: 14603-14610Abstract Full Text PDF PubMed Google Scholar), whereas GGT-I prefers proteins with the C-terminal CaaL or CaaF motif (4.Moores S.L. Schaber M.D. Mosser S.D. Rands E. O'Hara M.B. Garsky V.M. Marshall M.S. Pompliano D.L. Gibbs J.B. J. Biol. Chem. 1991; 266: 14603-14610Abstract Full Text PDF PubMed Google Scholar). Among well characterized Ras proteins that terminate with a CaaX motif, human H-Ras-CIMF, N-Ras-CVVM, K-RasA-CIIM, and Rap2-CNIQ are known to be farnesylated by FT, while Rap1A-CLLL, as well as Rho family proteins are geranylgeranylated by GGT-I. It has also been shown that K-RasB-CVIM can be either farnesylated by FT or geranylgeranylated by GGT-I (5.James G.L. Goldstein J.L. Brown M.S. J. Biol. Chem. 1995; 270: 6221-6226Abstract Full Text Full Text PDF PubMed Scopus (295) Google Scholar). Since constitutively active mutations of Ras proteins have been shown to induce carcinogenesis (6.Tabin C.J. Bradley S.M. Bargmann C.I. Weinberg R.A. Papageorge A.G. Scolnick E.M. Dhar R. Lowy D.R. Chang E.H. Nature. 1982; 300: 143-149Crossref PubMed Scopus (860) Google Scholar, 7.Reddy E.P. Reynold R.K. Santos E. Barbacid M. Nature. 1982; 300: 149-152Crossref PubMed Scopus (870) Google Scholar, 8.Taparowsky E. Suard Y. Fasano O. Shimizu K. Goldfarb M. Wigler M. Nature. 1982; 30: 762-765Crossref Scopus (447) Google Scholar), which is suppressed by the inhibition of farnesylation, FT has attracted attention as a target of cancer chemotherapy (9.Gibbs J.B. Cell. 1991; 65: 1-4Abstract Full Text PDF PubMed Scopus (330) Google Scholar). In addition, several compounds targeting FT have proven promising against African sleeping sickness caused by Trypanosoma brucei and Malaria caused by Plasmodia species (10.Gelb M.H. Van Voorhis W.C. Buckner F.S. Yokoyama K. Eastman R. Carpenter E.P. Panethymitaki C. Brown K.A. Smith D.F. Mol. Biochem. Parasitol. 2003; 126: 155-163Crossref PubMed Scopus (130) Google Scholar). Entamoeba histolytica is an intestinal protozoan parasite, which causes amebic dysentery, colitis, and liver abscess in humans, and is responsible for an estimated 50 million cases of amebiasis and 40-100 thousand deaths annually (11.World Health OrganizationBull. World Health Organ. 1997; 75: 291-292PubMed Google Scholar). A number of small GTPases have been studied including Ras/Rap (12.Shen P.-S. Lohia A. Samuelson J. Mol. Biochem. Parasitol. 1994; 64: 111-120Crossref PubMed Scopus (22) Google Scholar, 13.Shen P.-S. Sanford J.C. Samuelson J. Exp. Parasitol. 1996; 82: 65-68Crossref PubMed Scopus (9) Google Scholar), Rho/Rac (14.Lohia A. Samuelson J. Mol. Biochem. Parasitol. 1993; 58: 177-180Crossref PubMed Scopus (43) Google Scholar, 15.Lohia A. Samuelson J. Gene (Amst.). 1996; 173: 205-208Crossref PubMed Scopus (36) Google Scholar, 16.Ghosh S.K. Samuelson J. Infect. Immun. 1997; 65: 4243-42499Crossref PubMed Google Scholar, 17.Guilen N. Sansonetti P. Arch. Med. Res. 1997; 28: 129-131Google Scholar, 18.Guilen N. Boquet P. Sansonetti P. J. Cell Sci. 1998; 111: 1729-1739PubMed Google Scholar), and Rab (19.Temesvari L.A. Harris E.N. Stanley Jr., S.L. Cardelli J.A. Mol. Biochem. Parasitol. 1999; 103: 225-241Crossref PubMed Scopus (48) Google Scholar, 20.Juarez P. Sanchez-Lopez R. Ramos M.A. Stock R.P. Alagon A. Arch. Med. Res. 2000; 31: S157-S159Crossref PubMed Scopus (5) Google Scholar, 21.Saito-Nakano Y. Nakazawa M. Shigeta Y. Takeuchi T. Nozaki T. Mol. Biochem. Parasitol. 2001; 116: 219-222Crossref PubMed Scopus (25) Google Scholar). The completion of the E. histolytica genome data base will help us to comprehensively understand the presence and complexity of these small GTPases in the ameba. The molecular and cellular functions of some of these small GTPases have begun to be unveiled (12.Shen P.-S. Lohia A. Samuelson J. Mol. Biochem. Parasitol. 1994; 64: 111-120Crossref PubMed Scopus (22) Google Scholar, 17.Guilen N. Sansonetti P. Arch. Med. Res. 1997; 28: 129-131Google Scholar, 18.Guilen N. Boquet P. Sansonetti P. J. Cell Sci. 1998; 111: 1729-1739PubMed Google Scholar, 22.Rodríguez M.A. Garcia-Perez R.M. Garcia-Rivera G. Lopez-Reyes I. Mendoza L. Ortiz-Navarrete V. Orozco E. Mol. Biochem. Parasitol. 2000; 108: 199-206Crossref PubMed Scopus (42) Google Scholar). However, the molecular basis of the lipid modification of these small GTPases remains largely unknown in this parasite. In this report, we describe the molecular and biochemical characterization of the α- and β- subunits of FT of E. histolytica (EhFT) using recombinant proteins co-expressed in Escherichia coli. We also show that only one amebic Ras protein among the many small GTPases tested is farnesylated by EhFT. In addition, we show that the amebic FT exhibits marked resistance to a variety of compounds that are known to inhibit mammalian FT, indicating that the amebic FT possesses distinct biochemical properties from the mammalian FT. Parasite—Trophozoites of E. histolytica strain HM-1:IMSS cl6 (23.Diamond L.S. Mattern C.F. Bartgis I.L. J. Virol. 1972; 9: 326-341Crossref PubMed Google Scholar) were cultured axenically in BI-S-33 medium at 35.5 °C (24.Diamond L.S. Harlow D.R. Cunnick C.C. Trans. R. Soc. Trop. Med. Hyg. 1978; 72: 431-432Abstract Full Text PDF PubMed Scopus Google Scholar). human acid, acid, acid, and a were obtained from and pyrophosphate were from and obtained from and were from The other and used were from either or and of the of E. of E. histolytica using the and as T. T. F. M. K. Takeuchi T. Mol. Biochem. Parasitol. 1998; PubMed Scopus Google Scholar). and of and of E. to and from E. histolytica by a using and mammalian FT in the E. histolytica genome data base at The for The for and for were and respectively. Since we not a the C of in the data we used of the of to the using a of the as with the of at °C for by of at °C for at °C for and at °C for A at °C for used to the The were using a and the of using a sequences were with an an and of Ras of E. substrates for the amebic FT, we for putative Ras in the E. histolytica data base a using amebic and mammalian Ras as We identified putative Ras The C of these Ras proteins with or The two encoding putative Ras proteins the or to and in the E. histolytica genome data were to be to be farnesylated by the amebic FT, and EhRas4, respectively, and characterized A protein of and were by using as and the sequences in the genome data and protein sequences from E. histolytica and other and putative Ras and proteins of E. histolytica were from the and the for data using the and The protein and were with Res. 1994; PubMed Scopus Google Scholar) using the N. M. Mol. Biol. Google Scholar) with the using the Res. 1994; PubMed Scopus Google Scholar). were with 1996; Google Scholar). and J. PubMed Google Scholar) were from the of a to Recombinant the of the the and the binding between were by of using the recombinant R. M.A. A to and Scholar, 1995; PubMed Scopus Google Scholar). two of were to the and using a and an a and an of were using the of the as a the the by a and the binding a and an were the including the by the binding and a and were The of using a of the of the and and The with and and and to In the and in were of these two subunits at also in to of to Recombinant of and by and were by using as a and and and and and and and where are were and and to and The were to an to to an protein of and a or protein were using and with in The characterization of and and of the of these are and of Recombinant as were E. A at °C in medium of and of The of medium the The were for and the of to induce protein The were by at for and the at °C The recombinant proteins were to the the were in and and at for The to a with the and with the The recombinant FT proteins were with at a of as J.L. Yokoyama K. S.M. J.C. R. Buckner F.S. Van Voorhis W.C. M.H. J. Biol. Chem. 2001; Full Text Full Text PDF PubMed Scopus Google Scholar). The recombinant FT and Ras proteins were against the enzyme and and and with and respectively, at °C Protein were by the of Biochem. 72: PubMed Scopus Google Scholar) using Protein used as the protein Protein and of recombinant proteins were by as J. T. A Scholar). E. histolytica were with at in a and and to of and at for the to activity of recombinant FT and the of E. histolytica were for of pyrophosphate or pyrophosphate the recombinant small GTPases as human or The as D.L. Rands E. Schaber M.D. Mosser S.D. Gibbs J.B. 1992; 31: PubMed Scopus Google Scholar) with in the in a of 50 50 or pyrophosphate and to of the recombinant FT or of the E. histolytica The by the of either the recombinant enzyme or cell at °C for and by the of of in The were to at for the of of the were using a The were with of and to The from FT were also in the presence of known FT farnesylpyrophosphate and a the binding activity using and a as V. Sci. A. PubMed Scopus Google Scholar). of and of E. sequences of and obtained by were to sequences from the genome data base and The putative of and of and proteins of and amino with a molecular mass of 35.6 and 42.6 and a pI of and respectively. A for identified domains and M.S. 1992; Google Scholar) using the that and well signature domains shared by other organisms. one and α-subunit one and and The protein sequences of and were with those from other using the and were the in and any signal an targeting and any in including the and and also the of amino in these subunits from other organisms. showed and 24% identity with of and T. and identity with the of these respectively. the to be for A and J. Biol. Chem. 1997; Full Text Full Text PDF PubMed Scopus Google Scholar, P. R. R. J. 1998; Scopus Google Scholar, E. K.A. 2001; PubMed Scopus Google Scholar) are in and of and of and were the α- β-subunit of the amebic FT showed with to those from other while and proteins encoding α- and β-subunits formed well distinct These results were with the that subunits of EhFT from other of the presence of biochemical properties of EhFT of EhFT in E. of and and as proteins two major proteins with an of an molecular mass of and which to and respectively. The molecular mass of α- and β-subunits well with a of with the and C-terminal of and respectively, for the recombinant and 42.6 for or were the molecular mass of these proteins well with their identity not of these two also that an number of protein not of the recombinant EhFT using a molecular mass of not the recombinant and were as a the of by and the recombinant EhFT estimated to be by not and for of FT of the Recombinant EhFT against Ras for of pyrophosphate, the recombinant EhFT showed FT activity of of protein against human recombinant whereas showed activity against mutant of of which shown to be geranylgeranylated by human GGT-I. The of to the the activity of the recombinant EhFT not as shown for mammalian and FT, that EhFT also and for and of the Ras in E. the protein substrates of EhFT in the parasite, we for putative Ras proteins in the genome data base to the and human In to and which have been (12.Shen P.-S. Lohia A. Samuelson J. Mol. Biochem. Parasitol. 1994; 64: 111-120Crossref PubMed Scopus (22) Google Scholar), we putative proteins with the C-terminal CaaX these possess or with with at the C terminus, while has or We proteins possessing or as or EhRas4, and the other proteins as The of the we to that the of at one from the (12.Shen P.-S. Lohia A. Samuelson J. Mol. Biochem. Parasitol. 1994; 64: 111-120Crossref PubMed Scopus (22) Google Scholar), in a and of and amino with a molecular mass of and and a pI of and respectively. The showed that and together with the identified and binding sequences McCormick F. Nature. 1991; PubMed Scopus Google Scholar) and at a the binding McCormick F. Nature. 1991; PubMed Scopus Google Scholar) identity among the and also that together with and and were not studied in the with and whereas showed only to and the results of the protein and EhRas4, together with and new of the Ras/Rap and Rab proteins were to well by to and Rab proteins were in this of as a of tested substrate specificity of EhFT We together with as for EhFT substrates shown that mammalian and small GTPases with a C-terminal or have a to be farnesylated whereas those or at the C-terminal to be geranylgeranylated (4.Moores S.L. Schaber M.D. Mosser S.D. Rands E. O'Hara M.B. Garsky V.M. Marshall M.S. Pompliano D.L. Gibbs J.B. J. Biol. Chem. 1991; 266: 14603-14610Abstract Full Text PDF PubMed Google Scholar). The recombinant EhFT showed farnesyltransferase activity of of which to the activity human In EhFT showed or only activity We also tested or are farnesylated by EhFT. The recombinant EhFT not transfer farnesyl to or not the recombinant EhFT not geranylgeranyl pyrophosphate as a donor to transfer the geranylgeranyl residue to EhRas4, or not that and are of binding a binding and showed activity to and not We also for the FT activity in the of the E. histolytica Among the human H-Ras and E. histolytica Ras FT activity only against human and in the not which the that some other EhFT protein to these small in the amebic of showed the of recombinant EhFT for to be not that of FT, the of which for and is and D.L. Rands E. Schaber M.D. Mosser S.D. Gibbs J.B. 1992; 31: PubMed Scopus Google Scholar). of Recombinant EhFT to FT the of EhFT to known FT shown in EhFT at to to and when recombinant used as The of of EhFT to FT inhibitors not the EhFT also to these inhibitors when used as a of recombinant FT by inhibitors of human histolytica of human FT for the inhibitors using human as a protein substrate are shown for of human FT for the inhibitors using human as a protein substrate are shown for V. Brown N. R. Jr., E.M. Barbacid M. Res. 1995; Scopus Google J. K. J. 1992; PubMed Scopus Google J.B. Pompliano D.L. Mosser S.D. Rands E. Scolnick E.M. A. J. Biol. Chem. 1993; Full Text PDF PubMed Google Y. M.A. A. J. C.J. S.M. J. Biol. Chem. 1995; 270: Full Text Full Text PDF PubMed Scopus Google in a new In this we have for the the molecular identity of FT in enteric major of small i.e. Ras, Rho, Rac, and have been identified (12.Shen P.-S. Lohia A. Samuelson J. Mol. Biochem. Parasitol. 1994; 64: 111-120Crossref PubMed Scopus (22) Google Scholar, A. Samuelson J. Mol. Biochem. Parasitol. 1993; 58: 177-180Crossref PubMed Scopus (43) Google Scholar, 15.Lohia A. Samuelson J. Gene (Amst.). 1996; 173: 205-208Crossref PubMed Scopus (36) Google Scholar, 16.Ghosh S.K. Samuelson J. Infect. Immun. 1997; 65: 4243-42499Crossref PubMed Google Scholar, 17.Guilen N. Sansonetti P. Arch. Med. Res. 1997; 28: 129-131Google Scholar, 18.Guilen N. Boquet P. Sansonetti P. J. Cell Sci. 1998; 111: 1729-1739PubMed Google Scholar, L.A. Harris E.N. Stanley Jr., S.L. Cardelli J.A. Mol. Biochem. Parasitol. 1999; 103: 225-241Crossref PubMed Scopus (48) Google Scholar, 20.Juarez P. Sanchez-Lopez R. Ramos M.A. Stock R.P. Alagon A. Arch. Med. Res. 2000; 31: S157-S159Crossref PubMed Scopus (5) Google Scholar, 21.Saito-Nakano Y. Nakazawa M. Shigeta Y. Takeuchi T. Nozaki T. Mol. Biochem. Parasitol. 2001; 116: 219-222Crossref PubMed Scopus (25) Google Scholar) in E. histolytica and some of their functions studied N. Sansonetti P. Arch. Med. Res. 1997; 28: 129-131Google Scholar, 18.Guilen N. Boquet P. Sansonetti P. J. Cell Sci. 1998; 111: 1729-1739PubMed Google Scholar), this is the and characterization of an enzyme for and targeting of these small We identified common of FT in other and signature domains as and and the i.e. protein α-subunit repeats and repeats EhFT a with a of between α- and β-subunits, to the in other as shown by that and are from from other organisms. This some of the biochemical of the amebic FT not shared by the mammalian It is also that of α- and β-subunits are that the FT subunits at a in these organisms. We identified as one of the substrates of FT in E. not to small GTPases as substrates for EhFT, we showed that EhFT as a farnesyl In recombinant and were not farnesylated by recombinant EhFT or the cell The that the amebic the activity to transfer the farnesyl residue to EhRas4, but not other the that the FT characterized in the is the sole FT in this and also for this Ras We also that farnesylation is not a major of Ras protein in this It that EhFT not which with as a farnesyl mammalian and small GTPases a C-terminal or were shown to to be farnesylated (4.Moores S.L. Schaber M.D. Mosser S.D. Rands E. O'Hara M.B. Garsky V.M. Marshall M.S. Pompliano D.L. Gibbs J.B. J. Biol. Chem. 1991; 266: 14603-14610Abstract Full Text PDF PubMed Google Scholar). substrate specificity also for FT from protozoan parasite T. which Ras protein with but not K. Y. M.H. Mol. Biochem. Parasitol. 1997; PubMed Scopus Google Scholar). The that EhFT prefers amino at the C of and that the amebic FT possess a binding for the Ras C Among putative were the only that a terminal CaaX and also showed a to and to other small GTPases and This together with the of farnesylation by EhFT of and that protein is the sole Ras protein farnesylated by EhFT. It is also that proteins with the C-terminal or respectively, are farnesylated by GGT-I, as shown for Goldstein J.L. Brown M.S. J. Biol. Chem. 1995; 270: Full Text Full Text PDF PubMed Scopus Google Scholar). This is also the for which has been shown to be farnesylated by the recombinant E. histolytica GGT-I in not the C of the identified amebic Ras/Rap and (12.Shen P.-S. Lohia A. Samuelson J. Mol. Biochem. Parasitol. 1994; 64: 111-120Crossref PubMed Scopus (22) Google Scholar) to be a using a of and recombinant and showed that these proteins were not but farnesylated P.-S. Sanford J.C. Samuelson J. Exp. Parasitol. 1996; 82: 65-68Crossref PubMed Scopus (9) Google Scholar). that recombinant EhFT and we have to that the results of the P.-S. Sanford J.C. Samuelson J. Exp. Parasitol. 1996; 82: 65-68Crossref PubMed Scopus (9) Google Scholar) are a of farnesylation by heterologous as for which farnesylated by the GGT-I not is that the farnesylation of these small GTPases by GGT-I require an Rab protein for (3.Zang F.L. Casey P.J. Annu. Rev. Biochem. 1996; 65: 241-269Crossref PubMed Scopus (1743) Google Scholar), in E. these results suggest that the substrate specificity of among organisms. including the and characterization of GGT-I of E. histolytica to proteins are geranylgeranylated by the amebic GGT-I, are we not show a for EhRas4, this protein the domains of Ras McCormick F. Nature. 1991; PubMed Scopus Google Scholar) for and and showed a to other proteins in the We that of binding not identity as a small a cysteine residue amino of the C to be in and I. I. Marshall C.J. Cell. Full Text PDF PubMed Scopus Google Scholar), which shown to be for In addition, EhRas4, in contrast to also the which in and to Marshall C.J. Cell. Full Text PDF PubMed Scopus Google Scholar). The also in with a the of FTβ, which is in to the responsible for the binding to the Ras C Casey P.J. L.S. 1997; Scopus Google Scholar). which to with the and possesses a number of of with either or amino in Casey P.J. L.S. 1997; Scopus Google Scholar) and to It is that these for the that with which the Ras specificity of the amebic FT. In to acceptor the amebic FT differences in against compounds known to inhibit human FT by distinct Marked differences in to were the amino and of that were shown to be in the at the of the and to be for the with the E. K.A. 2001; PubMed Scopus Google Scholar) were inhibitors and acid the common farnesyl V. Sci. A. PubMed Scopus Google Scholar), which with these this Casey P.J. L.S. 1997; Scopus Google Scholar). the of of EhFT against these that the binding specificity of these compounds not the of the but the and The that EhFT is to I and acid whereas human FT is to these inhibitors well with the that EhFT has to the major differences between inhibitors I and the presence of the and the of the C-terminal residue in the differences in be by the of with amino in the amebic FT It is that EhFT is not to the human not a substrate of EhFT. of differences in the substrates and inhibitors between the mammalian and amebic FT us to or novel inhibitors for EhFT, to the development of new chemotherapeutics against amebiasis. We for and and for the and recombinant protein and We also for the of FT and for The data base with a E. histolytica genome data base at the for and with from of Health and The