Taverna Sean D, Ueberheide Beatrix M, Liu Yifan, Tackett Alan J, Diaz Robert L, Shabanowitz Jeffrey, Chait Brian T, Hunt Donald F, Allis C David
Laboratory of Chromatin Biology, The Rockefeller University, New York, NY 10021, USA.
Proc Natl Acad Sci U S A. 2007 Feb 13;104(7):2086-91. doi: 10.1073/pnas.0610993104. Epub 2007 Feb 6.
Individual posttranslational modifications (PTMs) on histones have well established roles in certain biological processes, notably transcriptional programming. Recent genomewide studies describe patterns of covalent modifications, such as H3 methylation and acetylation at promoters of specific target genes, or "bivalent domains," in stem cells, suggestive of a possible combinatorial interplay between PTMs on the same histone. However, detection of long-range PTM associations is often problematic in antibody-based or traditional mass spectrometric-based analyses. Here, histone H3 from a ciliate model was analyzed as an enriched source of transcriptionally active chromatin. Using a recently developed mass spectrometric approach, combinatorial modification states on single, long N-terminal H3 fragments (residues 1-50) were determined. The entire modification status of intact N termini was obtained and indicated correlations between K4 methylation and H3 acetylation. In addition, K4 and K27 methylation were identified concurrently on one H3 species. This methodology is applicable to other histones and larger polypeptides and will likely be a valuable tool in understanding the roles of combinatorial patterns of PTMs.
组蛋白上的单个翻译后修饰（PTM）在某些生物学过程中，尤其是转录编程中，已确立了其作用。最近的全基因组研究描述了共价修饰模式，例如干细胞中特定靶基因启动子处的H3甲基化和乙酰化，或“双价结构域”，这暗示了同一组蛋白上PTM之间可能存在组合相互作用。然而，在基于抗体或传统质谱分析中，检测长程PTM关联通常存在问题。在这里，对来自纤毛虫模型的组蛋白H3进行了分析，将其作为转录活性染色质的丰富来源。使用最近开发的质谱方法，确定了单个长N端H3片段（第1 - 50位残基）上的组合修饰状态。获得了完整N端的整体修饰状态，并表明了K4甲基化与H3乙酰化之间的相关性。此外，在一个H3物种上同时鉴定出了K4和K27甲基化。这种方法适用于其他组蛋白和更大的多肽，并且可能成为理解PTM组合模式作用的有价值工具。
