Structural insights into operator recognition by BioQ in the Mycobacterium smegmatis biotin synthesis pathway.
Structural insights into operator recognition by BioQ in the Mycobacterium smegmatis biotin synthesis pathway.
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DOI：
10.1016/j.bbagen.2018.05.015
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发表时间：
2018-09
期刊：
影响因子：
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通讯作者：
Ling Yan;Qing Tang;Z. Guan;K. Pei;Tingting Zou;Jin He
中科院分区：
文献类型：
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作者：
Ling Yan;Qing Tang;Z. Guan;K. Pei;Tingting Zou;Jin He
背景生物素是生物体中一种重要的辅因子。TetR家族转录调节因子（TFTR）BioQ是耻垢分枝杆菌中生物素合成的主要调节因子。BioQ通过与保守的回文DNA序列（BioQ操纵子）结合来抑制其靶基因的表达。然而，BioQ识别这种DNA元素的机制尚未完全阐明。Methods/resultsWe解决了BioQ同二聚体的晶体结构，在其apo形式和复杂的与其特定的运营商在2.26 <$和2.69 <$分辨率，分别。BioQ将每个原聚体的N-末端识别螺旋插入其操纵子的相应大沟中，并通过静电相互作用和氢键稳定复合物的形成，以诱导DNA和BioQ的构象变化。BioQ的DNA界面富含带正电荷的残基，有助于BioQ稳定DNA结合。我们首次阐明了BioQ识别DNA的结构基础，并通过进一步的定点突变鉴定了负责DNA结合的氨基酸残基。一般意义我们的发现清楚地阐明了BioQ识别生物素合成途径中操纵子的机制，揭示了BioQ不同于其他TFTR成员的独特结构特征。
BackgroundBiotin is an essential cofactor in living organisms. The TetR family transcriptional regulator (TFTR) BioQ is the main regulator of biotin synthesis in Mycobacterium smegmatis. BioQ represses the expression of its target genes by binding to a conserved palindromic DNA sequence (the BioQ operator). However, the mechanism by which BioQ recognizes this DNA element has not yet been fully elucidated.Methods/resultsWe solved the crystal structures of the BioQ homodimer in its apo-form and in complex with its specific operator at 2.26 Å and 2.69 Å resolution, respectively. BioQ inserts the N-terminal recognition helix of each protomer into the corresponding major grooves of its operator and stabilizes the formation of the complex via electrostatic interactions and hydrogen bonding to induce conformational changes in both the DNA and BioQ. The DNA interface of BioQ is rich in positively charged residues, which help BioQ stabilize DNA binding. We elucidated the structural basis of DNA recognition by BioQ for the first time and identified the amino acid residues responsible for DNA binding via further site-directed mutagenesis.General significanceOur findings clearly elucidate the mechanism by which BioQ recognizes its operator in the biotin synthesis pathway and reveal the unique structural characteristics of BioQ that are distinct from other TFTR members.