Evidence that the localization of the elongation factor Spt16 across transcribed genes is dependent upon histone H3 integrity in Saccharomyces cerevisiae
Evidence that the localization of the elongation factor Spt16 across transcribed genes is dependent upon histone H3 integrity in Saccharomyces cerevisiae
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DOI：
10.1534/genetics.106.067140
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发表时间：
2007-09-01
期刊：
影响因子：
3.3
通讯作者：
Winston, Fred
中科院分区：
文献类型：
--
作者：
Duina, Andrea A.;Rufiange, Anne;Winston, Fred
先前对酿酒酵母中组蛋白H3的研究发现了一个突变体，该突变体具有单个氨基酸变化，亮氨酸61变为色氨酸，这赋予了几种转录缺陷。我们现在提出了几条线的证据表明，这种H3突变体，H3-L 61 W，是受损的转录延伸的水平，可能是通过改变与保守的因子Spt 16，转录延伸复合物yFACT的一个亚基的相互作用。首先，对H3-L 61 W冷敏感表型的抑制子的选择已经鉴定了编码Spt 16的基因中的新突变。这些遗传相互作用是等位基因特异性的，表明H3和Spt 16之间的直接相互作用。第二，类似于其他几种延伸和染色质突变体，包括spt 16突变体，H3-L 61 W突变体允许从FLO 8编码区内的隐蔽启动子转录。最后，染色质免疫沉淀实验表明，在H3-L 61 W突变体中，Spt 16在转录区域上的结合谱发生了显著改变，在5 '-编码区域上的水平降低，而在3'区域上的水平升高。总之，这些和其他结果提供了强有力的证据表明，组蛋白H3的完整性是至关重要的，以确保适当的分布Spt 16跨转录基因，并提出了一个模型的机制，Spt 16通常从DNA中解离转录后。
A previous study of histone H3 in Saccharomyces cerevisiae identified a mutant with a single amino acid change, leucine 61 to tryptophan, that confers several transcriptional defects. We now present several lines of evidence that this H3 mutant, H3-L61W, is impaired at the level of transcription elongation, likely by altered interactions with the conserved factor Spt16, a subunit of the transcription elongation complex yFACT. First, a selection for suppressors of the H3-L61W cold-sensitive phenotype has identified novel mutations in the gene encoding Spt16. These genetic interactions are allele specific, suggesting a direct interaction between H3 and Spt16. Second, similar to several other elongation and chromatin mutants, including spt16 mutants, an H3-L61W mutant allows transcription from a cryptic promoter within the FLO8 coding region. Finally, chromatin-immunoprecipitation experiments show that in an H3-L61W Mutant there is a dramatically altered profile of Spt16 association over transcribed regions, with reduced levels over 5'-coding regions and elevated levels over the 3' regions. Taken together, these and other results provide strong evidence that the integrity of histone H3 is crucial for ensuring proper distribution of Spt16 across transcribed genes and suggest a model for the mechanism by which Spt16 normally dissociates from DNA following transcription.