Characterization of a novel trypanosomatid small nucleolar RNA

Alexander Levitan, Yu Xin Xu, Claudia Ben-Dov, Herzel Ben-Shlomo, Yafei Zhang, Shulamit Michaeli

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21 Scopus citations


Trypanosomes possess unique RNA processing mechanisms including trans-splicing of pre-mRNA and RNA editing of mitochondrial transcripts. The previous finding of a trimethylguanosine (TMG) capped U3 homologue in trypanosomes suggests that rRNA processing may be related to the processing in other eukaryotes. In this study, we describe the first trypanosomatid snoRNA that belongs to the snoRNAs that were shown to guide ribose methylation of rRNA. The RNA, identified in the monogenetic trypanosomatid Leptomonas collosoma, was termed snoRNA-2 and is encoded by a multi-copy gene. SnoRNA-2 is 85 nt long, it lacks a 5' cap and possesses the C and D boxes characteristic to all snoRNAs that bind fibrillarin. Computer analysis indicates a potential for base-pairing between snoRNA-2 and 5.8S rRNA, and 18S rRNA. The putative interaction domains obey the rules suggested for the interaction of guide snoRNA with its rRNA target for directing ribose methylation on the rRNA. However, mapping the methylated sites on the 5.8S rRNA and 18S rRNA indicates that the expected site on the 5.8S is methylated, whereas the site on the 18S is not. The proposed interaction with 5.8S rRNA is further supported by the presence of psoralen cross-link sites on snoRNA-2. GenBank search suggests that snoRNA-2 is not related to any published snoRNAs. Because of the early divergence of the Trypanosomatidae from the eukaryotic lineage, the presence of a methylating snoRNA that is encoded by a multi-copy gene suggests that methylating snoRNAs may have evolved in evolution from self-transcribed genes.

Original languageEnglish
Pages (from-to)1775-1783
Number of pages9
JournalNucleic Acids Research
Issue number7
StatePublished - 1 Apr 1998
Externally publishedYes

Bibliographical note

Funding Information:
This work was supported by the MINERVA foundation, Munich/ Germany, by the Leo and Julia Forchheimer Center for Molecular Genetics of the Weizmann Institute and by a research grant from the Cemach and Anna Oiserman Research Fund. We wish to thank Ora Asher for her excellent technical assistance.


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