Wright Jessica R, Siegel T Nicolai, Cross George A M
Laboratory of Molecular Parasitology, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA.
Mol Biochem Parasitol. 2010 Aug;172(2):141-4. doi: 10.1016/j.molbiopara.2010.03.013. Epub 2010 Mar 27.
Recent studies have identified histone modifications and suggested a role for epigenetic gene regulation in Trypanosoma brucei. The histone modification H4K10ac and histone variants H2AZ and H2BV localize to probable sites of transcription initiation. Although all T. brucei histones have very evolutionarily divergent N-terminal tails, histone H3 shows conservation with other eukaryotic organisms in 6 of 8 amino acids encompassing lysine 4. Tri-methylation of H3K4 is generally associated with transcription. We therefore generated a specific antibody to T. brucei H3K4me3 and performed chromosome immunoprecipitation and high-throughput sequencing. We show that H3K4me3 is enriched at the start of polycistronic transcription units at divergent strand-switch regions and at other sites of RNA polymerase II transcription reinitiation. H3K4me3 largely co-localizes with H4K10ac, but with a skew towards the upstream side of the H4K10ac peak, suggesting that it is a component of specific nucleosomes that play a role in Pol II transcription initiation.
近期研究已鉴定出组蛋白修饰，并提示了表观遗传基因调控在布氏锥虫中的作用。组蛋白修饰H4K10ac以及组蛋白变体H2AZ和H2BV定位于可能的转录起始位点。尽管所有布氏锥虫组蛋白的N端尾巴在进化上差异很大，但组蛋白H3在包含赖氨酸4的8个氨基酸中的6个氨基酸上与其他真核生物具有保守性。H3K4的三甲基化通常与转录相关。因此，我们制备了针对布氏锥虫H3K4me3的特异性抗体，并进行了染色体免疫沉淀和高通量测序。我们发现，H3K4me3在多顺反子转录单元起始处、分歧链切换区域以及RNA聚合酶II转录重新起始的其他位点富集。H3K4me3在很大程度上与H4K10ac共定位，但偏向于H4K10ac峰的上游侧，这表明它是在Pol II转录起始中起作用的特定核小体的一个组成部分。
