title: Cloning, characterization and subcellular localization of a Trypanosoma cruzi argonaute protein defining a new subfamily distinctive of trypanosomatids.
abstract: Over the last years an expanding family of small non-coding RNAs (sRNA) has been identified in eukaryotic genomes which behave as sequence-specific triggers for mRNA degradation, translation repression, heterochromatin formation and genome stability. To achieve their effectors functions, sRNAs associate with members of the Argonaute protein family. Argonaute proteins are segregated into three paralogous groups: the AGO-like subfamily, the PIWI-like subfamily, and the WAGO subfamily (for Worm specific AGO). Detailed phylogenetic analysis of the small RNA-related machinery components revealed that they can be traced back to the common ancestor of eukaryotes. However, this machinery seems to be lost or excessively simplified in some unicellular organisms such as Saccharomyces cerevisiae, Trypanosoma cruzi, Leishmania major and Plasmodium falciparum which are unable to utilize dsRNA to trigger degradation of target RNAs. We reported here a unique ORF encoding for an AGO/PIWI protein in T. cruzi which was expressed in all stages of its life cycle at the transcript as well as the protein level. Database search for remote homologues, revealed the presence of a divergent PAZ domain adjacent to the well supported PIWI domain. Our results strongly suggested that this unique AGO/PIWI protein from T. cruzi is a canonical Argonaute in terms of its domain architecture. We propose to reclassify all Argonaute members from trypanosomatids as a distinctive phylogenetic group representing a new subfamily of Argonaute proteins and propose the generic designation of AGO/PIWI-tryp to identify them. Inside the Trypanosomatid-specific node, AGO/PIWI-tryps were clearly segregated into two paralog groups designated as AGO-tryp and PIWI-tryp according to the presence or absence of a functional link with RNAi-related phenomena, respectively.
authors.affiliation: Functional Genomics Unit, Institut Pasteur de Montevideo, Mataojo 2020 CP11400 Montevideo, Uruguay. rgarcia@pasteur.edu.uy
authors.forename: Maria R
authors.initials: MR
authors.lastname: Garcia Silva
authors.forename: Juan P
authors.initials: JP
authors.lastname: Tosar
authors.forename: Magali
authors.initials: M
authors.lastname: Frugier
authors.forename: Sergio
authors.initials: S
authors.lastname: Pantano
authors.forename: Braulio
authors.initials: B
authors.lastname: Bonilla
authors.forename: Luis
authors.initials: L
authors.lastname: Esteban
authors.forename: Esteban
authors.initials: E
authors.lastname: Serra
authors.forename: Carlos
authors.initials: C
authors.lastname: Rovira
authors.forename: Carlos
authors.initials: C
authors.lastname: Robello
authors.forename: Alfonso
authors.initials: A
authors.lastname: Cayota
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D003001:Cloning, Molecular; D019143:Evolution, Molecular; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010802:Phylogeny; D015800:Protozoan Proteins / Q000032:analysis* / Q000737:chemistry; D034741:RNA, Small Interfering; D012689:Sequence Homology, Nucleic Acid; D014349:Trypanosoma cruzi / Q000145:classification* / Q000378:metabolism*
chemical_list: D015800:Protozoan Proteins; D034741:RNA, Small Interfering