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The structure and repertoire of small interfering RNAs in L eishmania ( V iannia) braziliensis reveal diversification in the trypanosomatid RNAi pathway
Author(s) -
Atayde Vanessa D.,
Shi Huafang,
Franklin Joseph B.,
Carriero Nicholas,
Notton Timothy,
Lye LonFye,
Owens Katherine,
Beverley Stephen M.,
Tschudi Christian,
Ullu Elisabetta
Publication year - 2013
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/mmi.12117
Subject(s) - biology , rna interference , leishmania braziliensis , trypanosoma brucei , small interfering rna , rna , rna silencing , trans acting sirna , leishmania , genetics , transcription (linguistics) , microbiology and biotechnology , gene , parasite hosting , leishmaniasis , linguistics , philosophy , world wide web , computer science , cutaneous leishmaniasis
Summary Among trypanosomatid protozoa the mechanism of RNA interference ( RNAi ) has been investigated in T rypanosoma brucei and to a lesser extent in L eishmania braziliensis . Although these two parasitic organisms belong to the same family, they are evolutionarily distantly related raising questions about the conservation of the RNAi pathway. Here we carried out an in‐depth analysis of small interfering RNAs ( siRNAs ) associated with L . braziliensis Argonaute1 ( L br AGO 1). In contrast to T . brucei , L eishmania siRNAs are sensitive to 3′ end oxidation, indicating the absence of blocking groups, and the L eishmania genome does not code for a HEN 1 RNA 2′‐ O ‐methyltransferase, which modifies small RNA 3′ ends. Consistent with this observation, ∼ 20% of siRNA 3′ ends carry non‐templated uridines. Thus siRNA biogenesis, and most likely their metabolism, is different in these organisms. Similarly to T . brucei , putative mobile elements and repeats constitute the major L eishmania siRNA ‐producing loci and AGO 1 ablation leads to accumulation of long transcripts derived from putative mobile elements. However, contrary to T . brucei , no siRNAs were detected from other genomic regions with the potential to form double‐stranded RNA , namely sites of convergent transcription and inverted repeats. Thus, our results indicate that organism‐specific diversification has occurred in the RNAi pathway during evolution of the trypanosomatid lineage.