Chromatin immunoprecipitation and microarray analysis reveal that TFIIB occupies the SL RNA gene promoter region in Trypanosoma brucei chromosomes

作者：Liu Wenzhe; Das Anish; Morales Rachel; Banday Mahrukh; Aris Virginie; Lukac David M; Soteropoulos Patricia; Wah David A; Palenchar Jennifer; Bellofatto Vivian^*

来源：Molecular and Biochemical Parasitology, 2012, 186(2): 139-142.

DOI：10.1016/j.molbiopara.2012.09.003

• Trypanosomes
• RNA synthesis
• SL RNA genes
• Trypanosoma brucei
• Chromatin immunoprecipitation
• TFIIB

RNA polymerase II (RNAP-II) synthesizes the m(7)G-capped Spliced Leader (SL) RNA and most protein-coding mRNAs in trypanosomes. RNAP-II recruitment to DNA usually requires a set of transcription factors that make sequence-specific contacts near transcriptional start sites within chromosomes. In trypanosomes, the transcription factor TFIIB is necessary for RNAP-II-dependent SL RNA transcription. However, the trypanosomal TFIIB (tTFIIB) lacks the highly basic DNA binding region normally found in the C-terminal region of TFIIB proteins. To assess the precise pattern of tTFIIB binding within the SL RNA gene locus, as well as within several other loci, we performed chromatin immunoprecipitation/microarray analysis using a tiled gene array with a probe spacing of 10 nucleotides. We found that tTFIIB binds non-randomly within the SL RNA gene locus mainly within a 220-nt long region that straddles the transcription start site. tTFIIB does not bind within the small subunit (SSU) rRNA locus, indicating that trypanosomal TFIIB is not a component of an RNAP-I transcriptional complex. Interestingly, discrete binding sites were observed within the putative promoter regions of two loci on different chromosomes. These data suggest that although trypanosomal TFIIB lacks a highly basic DNA binding region, it nevertheless localizes to discrete regions of chromatin that include the SL RNA gene promoter.

• 出版日期2012-12