ACETYLATION OF H4K4 IS CELL CYCLE REGULATED & MEDIATED BY HAT3 IN T BRUCEI

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 翻译后的组蛋白修饰已经在几个真核生物中得到了广泛的研究。有人提出，这些修饰构成了一个‘组蛋白密码’，它指定了转录调控的表观遗传信息。布氏锥虫具有有限数量的组蛋白修饰酶，意味着冗余较少，是研究单个组蛋白修饰和组蛋白修饰酶功能的极好系统。在这项研究中，我们研究了组蛋白H4(H4K4)的赖氨酸4的乙酰化反应，H4K4是布氏毛滴虫组蛋白中含量最丰富的乙酰化位点。由于布氏毛滴虫组蛋白的序列差异很大，我们产生了针对乙酰化和未修饰的H4K4的高度特异性抗体。分离细胞的免疫荧光显微镜和Western blotting显示，未修饰的H4K4在S期有较强的富集性，表明由于非共价结合因子，该位点被G1/G0特异性掩蔽。最后，我们证明了组蛋白乙酰转移酶3(HAT3)负责H4K4的乙酰化，并且用蛋白质合成抑制剂放线菌亚胺处理细胞时，几乎瞬间失去了未修饰的H4K4位点。由于HAT3位于核内，我们的发现表明，新合成的带有未修饰K4的组蛋白H4被迅速输入到核中，在那里它被乙酰化，可能是不可逆转的。描述这些结果的手稿已经出版： 在布氏锥虫中，组蛋白H4K4的乙酰化是由HAT3调控和介导的。首页--期刊主要分类--期刊细介绍--期刊题录与文摘--期刊详细文摘内容 摩尔微生物。2008年2月；67(4)：762-71。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Post-translational histone modifications have been studied intensively in several eukaryotes. It has been proposed that these modifications constitute a 'histone code' that specifies epigenetic information for transcription regulation. With a limited number of histone-modifying enzymes, implying less redundancy, Trypanosoma brucei represents an excellent system in which to investigate the function of individual histone modifications and histone-modifying enzymes. In this study, we characterized the acetylation of lysine 4 of histone H4 (H4K4), the most abundant acetylation site in T. brucei histones. Because of the large sequence divergence of T. brucei histones, we generated highly specific antibodies to acetylated and unmodified H4K4. Immunofluorescence microscopy and Western blots with sorted cells revealed a strong enrichment of unmodified H4K4 in S phase and suggested a G1/G0-specific masking of the site, owing to non-covalently binding factors. Finally, we showed that histone acetyltransferase 3 (HAT3) is responsible for H4K4 acetylation and that treatment of cells with the protein synthesis inhibitor cycloheximide led to an almost instantaneous loss of unmodified H4K4 sites. As HAT3 is located inside the nucleus, our findings suggest that newly synthesized histone H4 with an unmodified K4 is imported rapidly into the nucleus, where it is acetylated, possibly irreversibly. A manuscript describing these results has been published: Acetylation of histone H4K4 is cell cycle regulated and mediated by HAT3 in Trypanosoma brucei. Siegel TN, Kawahara T, Degrasse JA, Janzen CJ, Horn D, Cross GA. Mol Microbiol. 2008 Feb;67(4):762-71.