title: A novel type of single-stranded nucleic acid binding protein recognizing a highly frequent motif in the intergenic regions of Trypanosoma cruzi.
abstract: Regulation of gene expression in trypanosomatids is not yet well understood. Genes are organized in long polycistronic transcriptional units separated by intergenic regions that may contain the signaling information for nucleic acid processing. Poly-dinucleotides are frequent in these regions and have been proposed to be involved in regulation of gene expression. Previously, we have reported that [dT-dG] are highly frequent, asymmetrically strand distributed, and constitute targets for specific protein binding [Biochem. Biophys. Res. Commun. 287 (2001) 98]. Here, we present the purification and characterization of a new type of single stranded nucleic acid binding protein (Tc38) that recognizes specifically the motif poly[dT-dG] in this parasite. The protein has a deduced molecular weight of 38kDa and its salient characteristics include an isoelectric point of 9.34, a high frequency of Ser, Leu, and di-amino acids. Neither compositional nor architectural conserved domains could be detected in database searches. Recombinant Tc38 was expressed as a GST fusion protein, purified, and used to analyze target specificity by electrophoretic mobility shift assays. The unusual characteristics of the protein together with the peculiar features of the specific nucleic acid target suggest the existence of a novel event that may be involved in the mechanisms of gene expression in trypanosomatids.
authors.affiliation: Laboratorio de Interacciones Moleculares, Facultad de Ciencias, Universidad de la República, Montevideo, Uruguay.
authors.forename: María Ana
authors.initials: MA
authors.lastname: Duhagon
authors.forename: Bruno
authors.initials: B
authors.lastname: Dallagiovanna
authors.forename: Martín
authors.initials: M
authors.lastname: Ciganda
authors.forename: William
authors.initials: W
authors.lastname: Ruyechan
authors.forename: Noreen
authors.initials: N
authors.lastname: Williams
authors.forename: Beatriz
authors.initials: B
authors.lastname: Garat
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015139:Blotting, Southern; D015153:Blotting, Western; D002455:Cell Division; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000378:metabolism / Q000502:physiology*; D004591:Electrophoresis, Polyacrylamide Gel; D005786:Gene Expression Regulation; D015723:Gene Library; D005982:Glutathione Transferase / Q000378:metabolism; D008969:Molecular Sequence Data; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014349:Trypanosoma cruzi / Q000378:metabolism*
chemical_list: D004268:DNA-Binding Proteins; D011993:Recombinant Fusion Proteins; D011994:Recombinant Proteins; C477882:Tc38 protein, Trypanosoma cruzi; D005982:Glutathione Transferase