Lysine acetylation of the Mycobacterium tuberculosis HU protein modulates its DNA binding and genome organization
Lysine acetylation of the Mycobacterium tuberculosis HU protein modulates its DNA binding and genome organization
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DOI：
10.1111/mmi.13339
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发表时间：
2016-05-01
影响因子：
3.6
通讯作者：
Nagaraja, Valakunja
中科院分区：
文献类型：
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作者：
Ghosh, Soumitra;Padmanabhan, Bhavna;Nagaraja, Valakunja
类核相关蛋白 HU 是真细菌中的一种保守蛋白，对于维持类核组织和基因表达的整体调控是必需的。结核分枝杆菌 HU (MtHU) 与具有 114 个氨基酸长的羧基末端延伸的其他直系同源物不同，与真核组蛋白具有高度的序列相似性。在这项研究中，我们证明 MtHU 的 DNA 结合特性受到类似于真核组蛋白的翻译后修饰的调节。与大肠杆菌表达的重组蛋白不同，从结核分枝杆菌细胞中纯化的 MtHU 在多个赖氨酸残基上被乙酰化。使用免疫共沉淀测定，我们确定 Eis 是与 MtHU 相互作用并对其进行修饰的乙酰转移酶之一。尽管已知 Eis 可使氨基糖苷类乙酰化，但乙酰化动力学表明其对 MtHU 的蛋白质乙酰化活性很强。体外 Eis 在多个赖氨酸残基处修饰 MtHU，主要是位于羧基末端结构域的残基。 MtHU 的乙酰化导致 DNA 相互作用减少并改变 NAP 的 DNA 压缩能力。 Eis 的过度表达导致 HU 过度乙酰化和基因组解压缩。这些结果为细菌中赖氨酸乙酰化调节核仁结构提供了初步见解。
Nucleoid-associated protein HU, a conserved protein across eubacteria is necessary for maintaining the nucleoid organization and global regulation of gene expression. Mycobacterium tuberculosis HU (MtHU) is distinct from the other orthologues having 114 amino acid long carboxyl terminal extensions with a high degree of sequence similarity to eukaryotic histones. In this study, we demonstrate that the DNA binding property of MtHU is regulated by posttranslational modifications akin to eukaryotic histones. MtHU purified from M. tuberculosis cells is found to be acetylated on multiple lysine residues unlike the E. coli expressed recombinant protein. Using coimmunoprecipitation assay, we identified Eis as one of the acetyl transferases that interacts with MtHU and modifies it. Although Eis is known to acetylate aminoglycosides, the kinetics of acetylation showed that its protein acetylation activity on MtHU is robust. In vitro Eis modified MtHU at various lysine residues, primarily those located at the carboxyl terminal domain. Acetylation of MtHU caused reduced DNA interaction and alteration in DNA compaction ability of the NAP. Over-expression of the Eis leads to hyper-acetylation of HU and decompaction of genome. These results provide first insights into the modulation of the nucleoid structure by lysine acetylation in bacteria.