Functional consequences of evolutionary innovation in histone repertoires

项目摘要 组蛋白将DNA包装到染色质中，并调节所有以DNA为模板的生物学过程。 真核生物与其基本功能一致，组蛋白的突变或失调导致许多 疾病虽然核心组蛋白主要在基因组包装中起作用，但组蛋白变体可以取代经典组蛋白。 组蛋白位于独特的基因组位置，具有特殊的作用，如DNA损伤反应（DDR）或基因 表情尽管它们具有重要的功能，但组蛋白库经历了明显的谱系特异性变化， 变化这种通过基因融合、复制或序列趋异而产生的进化新奇性在人类中是出乎意料的。 保守的蛋白质家族，并暗示了序列创新的适应性优势。这项建议 将使用真核组蛋白H2 A库的进化创新来研究原因， 组蛋白进化更替的结果。最常见的真核H2 A库是 由核心组蛋白H2 A和组蛋白变体H2A.X和H2A.Z组成，它们参与DDR和基因 法规，分别。然而，两个进化的转变，都可能选择性有利，已经发生 在酵母和果蝇H2 A基因组中。在酵母中，H2A.X完全取代了典型的H2 A，可能改善了 DDR和影响过程，如减数分裂，依赖于DDR。在果蝇中，H2A.X与H2A.Z融合， 产生了一种独特的H2 Av变种这种融合在异染色质处富集DDR，这可能限制DDR- 转座事件转移到基因贫乏的区域。为了确定这些进化的功能后果， 通过创新，申请人将重新设计酵母和果蝇中的祖先真核H2 A库。 特别是在S。在酿酒酵母中，申请人将工程化核心H2 A和两种变体H2A.X和H2A.Z， 阻止H2A.X成为核心组蛋白（Aim 1）。In D.黑腹，融合组蛋白H2 Av将是 分离为H2A.X和H2A.Z解偶联DDR和基因调控功能（目的2）。更改 生物体染色质包装和相关的生物学功能，包括DNA修复，减数分裂，生育力， 转座将被询问。在目标3中，申请人将应用在目标1和2中学习的工具来学习 真核细胞核心H2 A的分化。组蛋白有尾部序列， 修饰并在更高级的染色质包装和蛋白质相互作用中发挥关键作用。高 真核组蛋白尾部的序列差异表明，尾部可以促进独特的谱系特异性 功能协调发展的通过在酵母和苍蝇中改造不同的尾部序列，Aim 3将揭示染色质的变化 包装，和过程的变化，如交配，和静止的酵母，生育和发展 苍蝇。为了启动这项工作，申请人需要在遗传学，基因组学和表型测定方面进行培训， 两种模式生物酵母和苍蝇通过利用她在进化分析方面的专业知识和 在酵母和苍蝇的同时，在未来的申请人将研究生物学基础 和组蛋白创新的后果，包括她自己以前的发现和共同进化的机制。

PROJECT SUMMARY Histone proteins package DNA into chromatin and regulate all DNA-templated biological processes in eukaryotes. Consistent with their essential function, mutations or misregulation of histones result in many diseases. While core histones primarily function in genome packaging, histone variants can replace canonical histones at unique genomic locations for specialized roles such as DNA damage response (DDR) or gene expression. Despite their essential functions, histone repertoires have undergone distinct lineage-specific changes. Such evolutionary novelty via gene fusions, duplications or sequence divergence is unexpected in conserved protein families and suggestive of an adaptive advantage for sequence innovation. This proposal will use evolutionary innovations in eukaryotic histone H2A repertoires to investigate the causes and consequences of evolutionary turnover of histone proteins. The most common eukaryotic H2A repertoire is made up of core histone H2A, and histone variants H2A.X and H2A.Z that are involved in DDR and gene regulation, respectively. However, two evolutionary shifts, both likely selectively advantageous, have occurred in yeast and Drosophila H2A repertoires. In yeast, H2A.X, entirely replaced canonical H2A, likely improving DDR and affecting processes like meiosis that depend on DDR. In Drosophila, H2A.X fused with H2A.Z giving rise to a unique H2Av variant. This fusion enriches DDR at heterochromatin which potentially restricts DDR- based transposition events to gene poor regions. To identify functional consequences of these evolutionary innovations, the applicant will re-engineer the ancestral eukaryotic H2A repertoire in yeast and flies. Specifically in S. cerevisiae, the applicant will engineer a core H2A and two variants H2A.X and H2A.Z, preventing H2A.X from being the core histone (Aim 1). In D. melanogaster, the fusion histone H2Av will be separated into H2A.X and H2A.Z uncoupling DDR and gene regulation functions (Aim 2). Changes to organismal chromatin packaging, and relevant biological functions including DNA repair, meiosis, fertility, and transposition will be interrogated. In Aim 3, the applicant will apply tools learnt in Aims 1 and 2 to study divergence of eukaryotic core H2A. Histones have tail sequences which are heavily post-translationally modified and play crucial roles for higher order chromatin packaging and protein interactions. The high sequence divergence across eukaryotic histone tails suggests that tails could facilitate unique lineage-specific functions. By engineering different tail sequences in yeast and flies, Aim 3 will reveal changes to chromatin packaging, and changes to processes such as mating, and quiescence in yeast, and fertility and development in flies. To launch this work, the applicant requires training in genetics, genomics, and phenotypic assays in two model organisms, yeast and flies. By leveraging, her expertise in evolutionary analyses and the power of well-established tools in yeast and flies simultaneously, in the future the applicant will study the biological basis and consequences of histone innovation including her own previous discoveries and co-evolving mechanisms.