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Molecular and Cellular Biology, April 2000, p. 2308-2316, Vol. 20, No. 7
Department of Microbiology and Center for
Microbial Pathogenesis, School of Medicine and Biomedical Sciences,
State University of New York at Buffalo, Buffalo, New York 14214
Received 12 August 1999/Returned for modification 12 October
1999/Accepted 13 January 2000
Although primary transcripts are polycistronic in the mitochondria
of Trypanosoma brucei, steady-state levels of mature,
monocistronic RNAs change throughout the parasitic life cycle. This
indicates that steady-state RNA abundance is controlled by
posttranscriptional mechanisms involving differential RNA stability. In
this study, in organello pulse-chase labeling experiments were used to
analyze the stability of different T. brucei mitochondrial
RNA populations. In this system, total RNA and rRNA are stable for many
hours. In contrast, mRNAs can be degraded by two biochemically distinct turnover pathways. The first pathway results in the rapid degradation of mRNA (half-life [t1/2] of 11 to 18 min)
and is dependent upon the presence of an mRNA poly(A) tail. Remarkably,
this pathway also requires the addition of UTP and therefore is termed
UTP dependent. The second pathway results in slow turnover of
mitochondrial mRNA (t1/2 of ~3 h) and is not
dependent upon the presence of an mRNA poly(A) tail or the addition of
exogenous UTP. In summary, these results demonstrate the presence of a
novel, UTP-dependent degradation pathway for T. brucei
mitochondrial mRNAs and reveal an unprecedented role for both UTP and
mRNA polyadenylation in T. brucei mitochondrial gene expression.
0270-7306/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.
UTP-Dependent and -Independent Pathways of mRNA
Turnover in Trypanosoma brucei Mitochondria
*
Corresponding author. Mailing address: State University
of New York at Buffalo, Department of Microbiology, School of Medicine and Biomedical Sciences, 138 Farber Hall, 3435 Main St., Buffalo, NY
14214-3000. Phone: (716) 829-3307. Fax: (716) 829-2158. E-mail: lread{at}acsu.buffalo.edu.
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