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首页> 外文期刊>Journal of Molecular Biology >Full-length structures of BenM and two variants reveal different oligomerization schemes for LysR-type transcriptional regulators.
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Full-length structures of BenM and two variants reveal different oligomerization schemes for LysR-type transcriptional regulators.

机译：BenM和两个变体的全长结构揭示了LysR型转录调节子的不同寡聚方案。

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摘要

BenM, a LysR-type transcriptional regulator (LTTR) from the bacterium Acinetobacter baylyi, responds synergistically to benzoate and cis,cis-muconate. With these effectors, BenM activates gene expression during benzoate consumption. Without effectors, BenM represses transcription. Here, X-ray crystallography was used to determine the full-length structures of BenM and two variants that activate transcription without benzoate or cis,cis-muconate: BenM(R156H) and BenM(E226K). Previous studies indicate that these regulators function as tetramers. Here, interconnections between subunits in the crystals prevented the formation of a closed oligomer and highlighted the inherent flexibility of this multidomain regulator. Nevertheless, analysis of subunit interfaces suggested the functional significance of key interactions. The structures of BenM and its variants were nearly identical, implying that transcriptional differences rely on factors beyond major conformational changes defined solely by sequence. Comparisons of BenM with other LTTRs, including unpublished structures in the Protein Data Bank, revealed extensive variation in the relative orientations of DNA-binding domains (DBDs) and effector-binding domains (EBDs). To form dimers, different LTTRs used similar interfaces between two EBDs, each containing two subdomains: EBD-I and EBD-II. Surprisingly, the dimers used three substantially different schemes to form higher-order oligomers. In one scheme used by BenM, oligomer assembly involved contacts between the EBD-II regions and the DBD regions of adjacent subunits. In another scheme, there were no contacts between the EBDs; only the DBDs were involved in tetramer formation. In the third scheme, the oligomer interface involved DBD and EBD-I/EBD-II contacts. These diverse schemes demonstrate novel variation in the oligomeric structures of individual LTTRs within this large and important family.
机译：BenM是一种来自Baycine不动杆菌的LysR型转录调节子（LTTR），对苯甲酸酯和顺式，顺式-粘康酸酯具有协同反应。利用这些效应子，BenM在苯甲酸酯消耗过程中激活基因表达。没有效应子，BenM会抑制转录。在这里，X射线晶体学用于确定BenM的全长结构，以及在没有苯甲酸酯或顺式，顺式-粘康酸酯的情况下激活转录的两个变体：BenM（R156H）和BenM（E226K）。先前的研究表明这些调节剂起四聚体的作用。在这里，晶体中亚基之间的互连阻止了封闭低聚物的形成，并突出了这种多域调节剂的固有灵活性。尽管如此，对亚基界面的分析表明了关键相互作用的功能意义。 BenM及其变体的结构几乎相同，这意味着转录差异依赖于仅由序列定义的主要构象变化以外的因素。 BenM与其他LTTR的比较，包括蛋白质数据库中未发布的结构，揭示了DNA结合域（DBD）和效应子结合域（EBD）相对方向的广泛差异。为了形成二聚体，不同的LTTR在两个EBD之间使用相似的接口，每个EBD包含两个子域：EBD-I和EBD-II。出人意料的是，二聚体使用三种基本不同的方案形成高阶低聚物。在BenM使用的一种方案中，低聚物组装涉及到相邻亚基的EBD-II区和DBD区之间的接触。在另一种方案中，EBD之间没有联系。只有DBD参与四聚体的形成。在第三方案中，低聚物界面涉及DBD和EBD-I / EBD-II接触。这些多样化的方案证明了在这个大而重要的家族中单个LTTR的寡聚结构的新颖变异。

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