Wellcome Centre for Cell Biology, University of Edinburgh, Edinburgh, United Kingdom.
Institute of Immunology and Infection Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom.
Elife. 2022 Sep 28;11:e83135. doi: 10.7554/eLife.83135.
Kinetoplastids are a highly divergent lineage of eukaryotes with unusual mechanisms for regulating gene expression. We previously surveyed 65 putative chromatin factors in the kinetoplastid . Our analyses revealed that the predicted histone methyltransferase SET27 and the Chromodomain protein CRD1 are tightly concentrated at RNAPII transcription start regions (TSRs). Here, we report that SET27 and CRD1, together with four previously uncharacterized constituents, form the SET27 promoter-associated regulatory complex (SPARC), which is specifically enriched at TSRs. SET27 loss leads to aberrant RNAPII recruitment to promoter sites, accumulation of polyadenylated transcripts upstream of normal transcription start sites, and conversion of some normally unidirectional promoters to bidirectional promoters. Transcriptome analysis in the absence of SET27 revealed upregulated mRNA expression in the vicinity of SPARC peaks within the main body of chromosomes in addition to derepression of genes encoding variant surface glycoproteins (VSGs) located in subtelomeric regions. These analyses uncover a novel chromatin-associated complex required to establish accurate promoter position and directionality.
动基体生物是真核生物中一个高度分化的谱系,其基因表达调控机制与众不同。我们之前对 65 种动基体生物的假定染色质因子进行了调查。我们的分析表明,预测的组蛋白甲基转移酶 SET27 和 Chromodomain 蛋白 CRD1 紧密集中在 RNAPII 转录起始区 (TSR)。在这里,我们报告 SET27 和 CRD1 与四个以前未被表征的成分一起形成 SET27 启动子相关调节复合物 (SPARC),该复合物特异性地富集在 TSR 上。SET27 的缺失导致 RNAPII 异常募集到启动子位点,正常转录起始位点上游的聚腺苷酸化转录本积累,以及一些正常单向启动子转变为双向启动子。在没有 SET27 的情况下进行的转录组分析显示,在染色体主体中 SPARC 峰附近的附近区域上调了 mRNA 表达,除了位于端粒区的编码变异表面糖蛋白 (VSG) 的基因的去阻遏。这些分析揭示了一种新的染色质相关复合物,该复合物需要建立准确的启动子位置和方向性。