n nnnThe maize (Zea mays) Opaque2 (O2) gene encodes an endosperm-specificbZIP-type transcription activator. In this study, we analyzedO2 targets for chromatin and DNA modifications and transcriptionfactors binding during endosperm development and in leaves.In leaves, O2 targets exhibit high cytosine methylation levelsand transcriptionally silent chromatin, enriched with histonesH3 dimethylated at Lys-9 (H3K9me2) and Lys-27 (H3K27me2). Transcriptionalactivation in the endosperm occurs through a two-step process,with an early potentiated state and a later activated state.The potentiated state has cytosine demethylation at symmetricsites, substitution of H3K9me2 and H3K27me2 with histones H3acetylated at Lys-14 (H3K14ac) and dimethylated at Lys-4 (H3K4me2),and increased DNaseI sensitivity. During the activated state,the mRNA of O2 targets accumulates in correspondence to RNPII,O2, and Ada2/Gcn5 coactivator binding. The active state alsoexhibits further increases of H3K14ac/H3K4me2 and DNaseI accessibilitylevels and deposition of histone H3 acetylated at Lys-9 andtrimethylated at Lys-4. Analysis of o2 mutants revealed thatO2 targets differ in their dependence on O2 activity for coactivatorrecruitment and for formation of specific chromatin modificationprofiles. These results indicate gene-specific involvement ofmechanisms that modify chromatin states in the O2-mediated regulationof transcription.展开▼
机译：ABSTRACTn n
n TOP n <字体颜色= 464c53>抽象 n 介绍 n 结果 n 讨论 n 方法 n 参考文献 n n nnn玉米（ Zea mays ） Opaque2 （ O2 ）基因编码胚乳m-specific bZIP型转录激活因子。在这项研究中，我们分析了 O2 目标在胚乳发育过程中和叶片中染色质和DNA修饰以及转录 因子结合的靶标。 在叶片中， O2 靶标表现出高胞嘧啶甲基化水平 和转录沉默染色质，富含在Lys-9（H3K9me2）处被二甲基化的组蛋白 H3和Lys-27（H3K27me2）。胚乳中的转录 激活通过两步过程发生，即 具有早期增强状态和后期激活状态。 增强状态具有胞嘧啶。在对称 位进行脱甲基，用组蛋白H3 取代H3K9me2和H3K27me2，在Lys-14（H3K14ac）乙酰化，在Lys-4（H3K4me2）进行二甲基化， SUP>并增加DNaseI敏感性。在激活状态下， O2 靶标的mRNA积累起来对应于RNPII， O2和Ada2 / Gcn5共激活因子结合。活性状态还 表现出H3K14ac / H3K4me2和DNaseI可及性 水平的进一步提高，以及在Lys-9处乙酰化的组蛋白H3的沉积和在Lys处三甲基化的 的甲基化-4。对 o2 突变体的分析表明， O2 靶标对共激活因子 活性的依赖性不同。 SUP>招聘并用于形成特定的染色质修饰 配置文件。这些结果表明 机制的基因特异性参与，这些机制在 O2 介导的转录调节 中修饰染色质状态。展开▼
