The Trypanosoma brucei RNA‐Binding Protein TbRRM1 is Involved in the Transcription of a Subset of RNA Pol II‐Dependent Genes

Abstract

It has been long thought that RNA Polymerase (Pol) II transcriptional regulation does not operate in trypanosomes. However, recent reports have suggested that these organisms could regulate RNA Pol II transcription by epigenetic mechanisms. In this paper, we investigated the role of TbRRM1 in transcriptional regulation of RNA Pol II‐dependent genes by focusing both in genes located in a particular polycistronic transcription unit (PTU) and in the monocistronic units of the SL‐RNA genes. We showed that TbRRM1 is recruited throughout the PTU, with a higher presence on genes than intergenic regions. However, its depletion leads both to the decrease of nascent RNA and to chromatin compaction only of regions located distal to the main transcription start site. These findings suggest that TbRRM1 facilitates the RNA Pol II transcriptional elongation step by collaborating to maintain an open chromatin state in particular regions of the genome. Interestingly, the SL‐RNA genes do not recruit TbRRM1 and, after TbRRM1 knockdown, nascent SL‐RNAs accumulate while the chromatin state of these regions remains unchanged. Although it was previously suggested that TbRRM1 could regulate RNA Pol II‐driven genes, we provide here the first experimental evidence which involves TbRRM1 to transcriptional regulation.

Interactions of the Trypanosoma brucei brucei zinc-finger-domain protein ZC3H28

“…This was the only copurified protein that has any link with mRNA degradation. Some of the ZC3H28-linked RNA-binding proteins are implicated in splicing control: these include the putative regulators TSR1 (Gupta et al ., 2014 ) and HNRNPF/H (Gupta et al ., 2013 ), which are probably also associated with cytosolic mRNAs; and TRRM1, which has been implicated in transcription elongation (Levy et al ., 2015 ; Naguleswaran et al ., 2015 ; Banuelos et al ., 2019 ).…”

Interactions of the Trypanosoma brucei brucei zinc-finger-domain protein ZC3H28

“…Interestingly, ZC3H28 was specifically associated with just one of the five known EIF4E-EIF4G translation initiation complexes, EIF4E4-EIF4G3. Various splicing factors also co-purified, including the putative regulators TSR1 (Gupta et al ., 2014) HNRNPF/H (Gupta et al ., 2013), which are probably also associated with cytosolic mRNAs; and TRRM1 which has been implicated in transcription elongation (Banuelos et al ., 2019; Levy et al ., 2015; Naguleswaran et al ., 2015). Considering just proteins present in all three ZC3H28 purifications, the RNA-binding proteins ALBA1, ALBA2, DRBD2, ZC3H34 and ZC3H41 were also associated with both PABP1 and PABP2; HNRNPF/H,TSR1, TRRM1, ZC3H39 and ZC3H40 were associated with PABP2, and ALBA3 with PABP1 (Zoltner et al ., 2018).…”

Depolymerization of SUMO chains induces slender to stumpy differentiation in T. brucei bloodstream parasites

“…Reactions were incubated at 42°C for 50 minutes and then at 70°C for 15 minutes. Quantitative PCR assays were carried out in the 7500 Real Time PCR System from Applied Biosystems using SensiFAST SYBR Lo-ROX Kit (BioLine, London, UK) and primers previously described [ 9 , 60 ].…”