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PLoS Pathog. 2009 Aug;5(8):e1000565. doi: 10.1371/journal.ppat.1000565. Epub 2009 Aug 28.

Trypanosoma brucei PUF9 regulates mRNAs for proteins involved in replicative processes over the cell cycle.

Author information

1
Zentrum für Molekulare Biologie Heidelberg, DKFZ-ZMBH Allianz, Heidelberg, Germany. s.archer@zmbh.uni-heidelberg.de

Abstract

Many genes that are required at specific points in the cell cycle exhibit cell cycle-dependent expression. In the early-diverging model eukaryote and important human pathogen Trypanosoma brucei, regulation of gene expression in the cell cycle and other processes is almost entirely post-transcriptional. Here, we show that the T. brucei RNA-binding protein PUF9 stabilizes certain transcripts during S-phase. Target transcripts of PUF9--LIGKA, PNT1 and PNT2--were identified by affinity purification with TAP-tagged PUF9. RNAi against PUF9 caused an accumulation of cells in G2/M phase and unexpectedly destabilized the PUF9 target mRNAs, despite the fact that most known Puf-domain proteins promote degradation of their target mRNAs. The levels of the PUF9-regulated transcripts were cell cycle dependent, peaking in mid- to late- S-phase, and this effect was abolished when PUF9 was targeted by RNAi. The sequence UUGUACC was over-represented in the 3' UTRs of PUF9 targets; a point mutation in this motif abolished PUF9-dependent stabilization of a reporter transcript carrying the PNT1 3' UTR. LIGKA is involved in replication of the kinetoplast, and here we show that PNT1 is also kinetoplast-associated and its over-expression causes kinetoplast-related defects, while PNT2 is localized to the nucleus in G1 phase and redistributes to the mitotic spindle during mitosis. PUF9 targets may constitute a post-transcriptional regulon, encoding proteins involved in temporally coordinated replicative processes in early G2 phase.

PMID:
19714224
PMCID:
PMC2727004
DOI:
10.1371/journal.ppat.1000565
[Indexed for MEDLINE]
Free PMC Article

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