Methyl-dependent and spatial-specific DNA recognition by the orthologous transcription factors human AP-1 and Epstein-Barr virus Zta.
Methyl-dependent and spatial-specific DNA recognition by the orthologous transcription factors human AP-1 and Epstein-Barr virus Zta.
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DOI：
10.1093/nar/gkx057
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发表时间：
2017-03-17
影响因子：
14.9
通讯作者：
Cheng X
中科院分区：
文献类型：
--
作者：
Hong S;Wang D;Horton JR;Zhang X;Speck SH;Blumenthal RM;Cheng X
激活蛋白 1 (AP-1) 是一种转录因子，可识别两个版本的 7 碱基对响应元件，即 5΄-TGAGTCA-3΄ 或 5΄-MGAGTCA-3΄（其中 M = 5-甲基胞嘧啶）。这两个元件的共同特征是，5-甲基胞嘧啶和胸腺嘧啶在嘧啶的同一个位置（即5-碳）处都有一个甲基，因此它们各自在5΄端的第1和第5位核苷酸处都有两个甲基，从而在双链DNA中对称地分布有四个甲基。 Epstein-Barr 病毒 Zta 是病毒裂解周期的关键转录调节因子，与 AP-1 同源。 Zta 可识别多个甲基化 Zta 响应元件，包括 meZRE1 (5΄-TGAGMCA-3΄) 和 meZRE2 (5΄-TGAGMGA-3΄)，其中甲基化胞嘧啶占据与 AP-1 元件相对应的内部胸腺嘧啶残基之一，从而产生四个空间等效的甲基。在这里，我们研究 AP-1 和 Zta 如何识别其同源响应元件中的这些甲基。这些甲基与 AP-1 二聚体中的保守二丙氨酸（Jun 中的 Ala265 和 Ala266）或相应的 Zta 残基 Ala185 和 Ser186（通过其侧链碳 Cβ 原子）进行范德华接触。此外，两个 ZRE 元件在碱基对 6 处不同（C:G 与 G:C），形成伪对称序列 (meZRE1) 或不对称序列 (meZRE2)。体外 DNA 结合测定表明，Zta 对所检查的所有四个序列都具有高亲和力，而 AP-1 对不对称序列 (meZRE2) 的亲和力显着降低。我们将这种差异归因于 Zta Ser186（Zta 的独特残基），其侧链羟基氧原子与两个半位点的相互作用不同，而 AP-1 Jun 蛋白相应的 Ala266 缺乏这种灵活性。我们的分析证明了通过基本亮氨酸拉链转录因子以甲基化依赖性、空间和序列特异性方法识别 5mC/T 的新机制。
Activator protein 1 (AP-1) is a transcription factor that recognizes two versions of a 7-base pair response element, either 5΄-TGAGTCA-3΄ or 5΄-MGAGTCA-3΄ (where M = 5-methylcytosine). These two elements share the feature that 5-methylcytosine and thymine both have a methyl group in the same position, 5-carbon of the pyrimidine, so each of them has two methyl groups at nucleotide positions 1 and 5 from the 5΄ end, resulting in four methyl groups symmetrically positioned in duplex DNA. Epstein-Barr Virus Zta is a key transcriptional regulator of the viral lytic cycle that is homologous to AP-1. Zta recognizes several methylated Zta-response elements, including meZRE1 (5΄-TGAGMCA-3΄) and meZRE2 (5΄-TGAGMGA-3΄), where a methylated cytosine occupies one of the inner thymine residues corresponding to the AP-1 element, resulting in the four spatially equivalent methyl groups. Here, we study how AP-1 and Zta recognize these methyl groups within their cognate response elements. These methyl groups are in van der Waals contact with a conserved di-alanine in AP-1 dimer (Ala265 and Ala266 in Jun), or with the corresponding Zta residues Ala185 and Ser186 (via its side chain carbon Cβ atom). Furthermore, the two ZRE elements differ at base pair 6 (C:G versus G:C), forming a pseudo-symmetric sequence (meZRE1) or an asymmetric sequence (meZRE2). In vitro DNA binding assays suggest that Zta has high affinity for all four sequences examined, whereas AP-1 has considerably reduced affinity for the asymmetric sequence (meZRE2). We ascribe this difference to Zta Ser186 (a unique residue for Zta) whose side chain hydroxyl oxygen atom interacts with the two half sites differently, whereas the corresponding Ala266 of AP-1 Jun protein lacks such flexibility. Our analyses demonstrate a novel mechanism of 5mC/T recognition in a methylation-dependent, spatial and sequence-specific approach by basic leucine-zipper transcriptional factors.