Open AccessDegradation of the unstable EP1 mRNA in Trypanosoma brucei involves initial destruction of the 3'-untranslated region
Author(s) -
Henriette Irmer
Publication year - 2001
Publication title -
nucleic acids research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 9.008
H-Index - 537
eISSN - 1362-4954
pISSN - 0305-1048
DOI - 10.1093/nar/29.22.4707
Subject(s) - biology , trypanosoma brucei , untranslated region , messenger rna , rna , three prime untranslated region , microbiology and biotechnology , au rich element , transcription (linguistics) , gene , genetics , linguistics , philosophy
Kinetoplastid protozoa regulate their gene expression primarily through control of mRNA degradation and translation. We describe here the degradation of three reporter mRNAs in Trypanosoma brucei. One mRNA had the 3'-untranslated region (3'-UTR) from the developmentally regulated EP1 mRNA, which is abundant in the procyclic (tsetse fly) form of the parasite but is almost undetectable in the bloodstream form. This untranslated region includes a 26 nt U-rich sequence that causes extreme RNA instability in the bloodstream form. The two other RNAs, which are not developmentally regulated, had either the actin 3'-UTR, or a version of the EP1 sequence lacking the 26 nt bloodstream-form instability element. All RNAs had poly(A) tails approximately 200 nt long, in both bloodstream and procyclic forms. Degradation of the two constitutively expressed mRNAs involved deadenylation and degradation by both 5'-->3' and 3'-->5' exonucleases. In contrast, in bloodstream forms, the 3'-end of the RNA bearing the bloodstream-form instability element disappeared very rapidly after transcription inhibition and partially deadenylated intermediates were not seen. The instability element may cause extremely rapid deadenylation, or it may be targeted by an endonuclease.