title: Members of a large retroposon family are determinants of post-transcriptional gene expression in Leishmania.
abstract: Trypanosomatids are unicellular protists that include the human pathogens Leishmania spp. (leishmaniasis), Trypanosoma brucei (sleeping sickness), and Trypanosoma cruzi (Chagas disease). Analysis of their recently completed genomes confirmed the presence of non-long-terminal repeat retrotransposons, also called retroposons. Using the 79-bp signature sequence common to all trypanosomatid retroposons as bait, we identified in the Leishmania major genome two new large families of small elements--LmSIDER1 (785 copies) and LmSIDER2 (1,073 copies)--that fulfill all the characteristics of extinct trypanosomatid retroposons. LmSIDERs are approximately 70 times more abundant in L. major compared to T. brucei and are found almost exclusively within the 3'-untranslated regions (3'UTRs) of L. major mRNAs. We provide experimental evidence that LmSIDER2 act as mRNA instability elements and that LmSIDER2-containing mRNAs are generally expressed at lower levels compared to the non-LmSIDER2 mRNAs. The considerable expansion of LmSIDERs within 3'UTRs in an organism lacking transcriptional control and their role in regulating mRNA stability indicate that Leishmania have probably recycled these short retroposons to globally modulate the expression of a number of genes. To our knowledge, this is the first example in eukaryotes of the domestication and expansion of a family of mobile elements that have evolved to fulfill a critical cellular function.
authors: Laboratoire de Génomique Fonctionnelle des Trypanosomatides, Université Victor Segalen Bordeaux 2, Bordeaux, France. bringaud@u-bordeaux2.fr
authors: Frédéric
authors: F
authors: Bringaud
authors: Michaela
authors: M
authors: Müller
authors: Gustavo Coutinho
authors: GC
authors: Cerqueira
authors: Martin
authors: M
authors: Smith
authors: Annie
authors: A
authors: Rochette
authors: Najib M A
authors: NM
authors: El-Sayed
authors: Barbara
authors: B
authors: Papadopoulou
authors: Elodie
authors: E
authors: Ghedin
mesh_terms: D020413:3' Untranslated Regions / Q000737:chemistry; D000818:Animals; D001483:Base Sequence; D005075:Biological Evolution; D015536:Down-Regulation; D005786:Gene Expression Regulation / Q000502:physiology*; D018503:Genome, Protozoan / Q000235:genetics*; D007891:Leishmania / Q000235:genetics* / Q000502:physiology*; D018320:Leishmania major / Q000235:genetics; D008969:Molecular Sequence Data; D012333:RNA, Messenger / Q000378:metabolism; D018626:Retroelements / Q000502:physiology*; D016415:Sequence Alignment; D014346:Trypanosoma brucei brucei / Q000235:genetics; D014349:Trypanosoma cruzi / Q000235:genetics
chemical_list: D020413:3' Untranslated Regions; D012333:RNA, Messenger; D018626:Retroelements