title: TcRho1, a farnesylated Rho family homologue from Trypanosoma cruzi: cloning, trans-splicing, and prenylation studies.
abstract: Rho GTPases are members of the Ras superfamily and are involved in signal transduction pathways, including maintenance of cell morphology and motility, cell cycle progression, and transcription activation. We report the molecular identification in trypanosomatids (Trypanosoma cruzi) of the first member of the Rho family. The cloned Rho protein, TcRho1, shares approximately 40% homology with other members of the Rho family. Southern blot analysis revealed that TcRHO1 is a single copy gene per haploid genome, and Northern blot assays showed a transcript of 1200 nucleotides in length. Mapping the 5'-untranslated region of TcRHO1 transcripts revealed at least five different transcripts derived from differential trans-splicing. Three of the five transcripts contain the trans-splicing site within the coding region of the TcRHO1 gene. TcRho1 also contains the C-terminal sequence CQLF (CAAX motif), which is predicted to direct post-translation prenylation of the cysteine residue. A synthetic peptide containing this C-terminal motif, when tested against Q-Sepharose chromatography fractions from T. cruzi cytosol, was shown to be efficiently farnesylated, but not geranylgeranylated, despite the fact that the CAAX motif with X = Phe specifies geranylgeranylation by mammalian protein geranylgeranyltransferase I. Furthermore, immunoblot analyses of epimastigote protein with anti-S-farnesylcysteine methyl ester and anti-TcRho1 antisera strongly suggested that TcRho1 is farnesylated in vivo. The farnesylation of proteins such as Rho GTPases could be the basis for the selective cytotoxic action of protein farnesyltransferase inhibitors on trypanosomatids versus mammalian cells.
authors.affiliation: Instituto de Biofisica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21949, Brazil.
authors.forename: J L
authors.initials: JL
authors.lastname: Nepomuceno-Silva
authors.forename: K
authors.initials: K
authors.lastname: Yokoyama
authors.forename: L D
authors.initials: LD
authors.lastname: de Mello
authors.forename: S M
authors.initials: SM
authors.lastname: Mendonca
authors.forename: J C
authors.initials: JC
authors.lastname: Paixão
authors.forename: R
authors.initials: R
authors.lastname: Baron
authors.forename: J C
authors.initials: JC
authors.lastname: Faye
authors.forename: F S
authors.initials: FS
authors.lastname: Buckner
authors.forename: W C
authors.initials: WC
authors.lastname: Van Voorhis
authors.forename: M H
authors.initials: MH
authors.lastname: Gelb
authors.forename: U G
authors.initials: UG
authors.lastname: Lopes
mesh_terms: D020121:5' Untranslated Regions; D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D015139:Blotting, Southern; D015153:Blotting, Western; D002847:Chromatography, Agarose; D002874:Chromosome Mapping; D003001:Cloning, Molecular; D003545:Cysteine / Q000737:chemistry; D004591:Electrophoresis, Polyacrylamide Gel; D015723:Gene Library; D015151:Immunoblotting; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry; D010802:Phylogeny; D017368:Protein Prenylation; D011499:Protein Processing, Post-Translational; D015800:Protozoan Proteins; D012326:RNA Splicing; D012333:RNA, Messenger / Q000378:metabolism; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D014162:Transfection; D014349:Trypanosoma cruzi / Q000737:chemistry*; D020741:rho GTP-Binding Proteins / Q000737:chemistry* / Q000235:genetics*
chemical_list: D020121:5' Untranslated Regions; D010455:Peptides; D015800:Protozoan Proteins; D012333:RNA, Messenger; C434054:Rho1 protein, Trypanosoma cruzi; D020741:rho GTP-Binding Proteins; D003545:Cysteine