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首页> 外文学位 >Etude de la variante d'histone H2A.Z et du cycle de phosphorylation de l'ARN polymerase II chez Saccharomyces cerevisiae .
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Etude de la variante d'histone H2A.Z et du cycle de phosphorylation de l'ARN polymerase II chez Saccharomyces cerevisiae .

机译：酿酒酵母中组蛋白变体H2A.Z和RNA聚合酶II磷酸化周期的研究。

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摘要

Chromatin is more than just the eucaryotic DNA packaging system; it is the substrate of all reactions involving DNA in eukaryotic cells and actively regulates RNA Polymerase II (RNAPolII) access to DNA. Responsible for all mRNA transcription in eucaryotes, the RNAPolII must, following its recruitment to the preinitiation complex, overcome the chromatin barrier in order to transcribe genes. The RNAPolII CTD allows for the co-transcriptional coordination of mRNA maturation and chromatin modifications. The work covered in this thesis addresses two aspects of transcription: the chromatin substrate, with the localization of H2A variant, H2A.Z, and the transcription complex with the phosphorylation cycle of the RNAPolII CTD.;Following the introduction, chapter 2 constitutes a detailed and annotated Saccharomyces cerevisiae ChIP-chip protocol, from the culture to the hybridization of the array, with an emphasis on the proper controls required for chromatin study. This technique, extremely powerful for the in vivo study of all DNA transactions, leads to a better understanding of chromatin function in nuclear phenomena, thanks to the localization of histone variants and modifications.;The third chapter maps the H2A.Z variant across the yeast genome at ∼300 base pairs resolution using ChIP-chip. Our data shows that H2A.Z is incorporated into one or two promoter-bound nucleosomes at the majority of genes. H2A.Z enrichment is anticorrelated with transcription, and the results suggest that it configures chromatin structure to poise genes for transcriptional activation. Furthermore, we have shown that H2A.Z can regulate nucleosome positioning.;The next chapter focuses on the transcription machinery and, more precisely, on the phosphorylation cycle of RNAPolII. The CTD contains repetitions of a heptapeptide (Y1S2P3T4S 5P6S7) on which all serines are differentially phosphorylated along genes in a prescribed pattern during the transcription cycle. Here, we systematically profiled the location of the RNAPII phospho-isoforms in wild-type cells and mutants for most CTD modifying enzymes. The results provide evidence for a uniform CTD cycle across genes. Together with results from in vitro assays, these data reveal a complex interplay between the modifying enzymes, identify Ssu72 as the Ser7 phosphatase and show that proline isomerization is a key regulator of CTD dephosphorylation at the end of genes. Moreover, it reinforces the notion of variants of the phosphorylation marks, even though the exact nature of the variant is still difficult to identify.;The discussion introduces the studies that followed this work, including new projects conceived in our lab. Key.
机译：染色质不仅仅是真核DNA包装系统；它是真核细胞中涉及DNA的所有反应的底物，并积极调节RNA聚合酶II（RNAPolII）对DNA的访问。负责真核生物中的所有mRNA转录，RNAPolII在募集到预启动复合体后必须克服染色质屏障才能转录基因。 RNAPolII CTD可实现mRNA成熟度和染色质修饰的共转录协调。本文涉及的工作涉及转录的两个方面：染色质底物（具有H2A变体H2A.Z的定位）和转录复合物（具有RNAPolII CTD的磷酸化周期）。在引言之后，第2章详细介绍了转录过程。以及带有注释的酿酒酵母ChIP芯片方案，从培养到阵列杂交，重点是染色质研究所需的适当对照。由于组蛋白变体和修饰的定位，这项技术对于所有DNA交易的体内研究都极为强大，通过对组蛋白变体和修饰的定位，可以更好地理解核现象中的染色质功能。第三章在酵母中绘制了H2A.Z变体图使用ChIP芯片以约300个碱基对的分辨率解析基因组我们的数据表明，H2A.Z在大多数基因中被掺入一个或两个与启动子结合的核小体中。 H2A.Z富集与转录反相关，结果表明，它可以配置染色质结构来平衡基因的转录激活。此外，我们已经证明H2A.Z可以调节核小体的定位。下一章着重于转录机制，更准确地说，是RNAPolII的磷酸化周期。 CTD包含七肽（Y1S2P3T4S 5P6S7）的重复序列，在转录周期中，所有丝氨酸均沿基因以规定的模式差异磷酸化。在这里，我们系统地分析了野生型细胞和大多数CTD修饰酶突变体中RNAPII磷酸同工型的位置。结果为跨基因的均匀CTD循环提供了证据。连同体外测定的结果一起，这些数据揭示了修饰酶之间的复杂相互作用，将Ssu72鉴定为Ser7磷酸酶，并表明脯氨酸异构化是基因末端CTD去磷酸化的关键调节因子。此外，它增强了磷酸化标记变体的概念，即使该变体的确切性质仍然难以识别。讨论中介绍了跟随这项工作的研究，包括我们实验室中设想的新项目。键。

著录项

  • 作者

    Bataille, Alain R.;

  • 作者单位

    Universite de Montreal (Canada).;

  • 授予单位 Universite de Montreal (Canada).;
  • 学科 Biology Genetics.;Chemistry Biochemistry.
  • 学位 Ph.D.
  • 年度 2012
  • 页码 252 p.
  • 总页数 252
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 肿瘤学;
  • 关键词

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