The Solution Structures and Interaction of SinR and SinI: Elucidating the Mechanism of Action of the Master Regulator Switch for Biofilm Formation in Bacillus subtilis
The Solution Structures and Interaction of SinR and SinI: Elucidating the Mechanism of Action of the Master Regulator Switch for Biofilm Formation in Bacillus subtilis
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DOI：
10.1016/j.jmb.2019.08.019
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发表时间：
2020-01-17
影响因子：
5.6
通讯作者：
Cavanagh, John
中科院分区：
文献类型：
--
作者：
Milton, Morgan E.;Draughn, G. Logan;Cavanagh, John
细菌已经开发了许多保护策略，以确保在恶劣环境中生存，也许最强大的方法是形成保护性生物膜。在生物膜中，细菌细胞嵌入由多糖、蛋白质和DNA的复杂混合物组成的基质中。革兰氏阳性菌枯草芽孢杆菌已成为研究指导生物膜形成的调控网络的模式生物。从增殖状态到生物膜状态的表型转变受转录抑制因子SinR的活性及其主要拮抗剂SinI的失活调节。在这项工作中，我们提出了第一个全长结构模型的四聚体SinR使用混合的方法相结合的高分辨率溶液核磁共振（NMR），化学交联，质谱和分子对接。我们还提出了解决方案的NMR结构的拮抗剂SinI二聚体和探针背后的SinR-SinI相互作用的机制，使用生物化学和生物物理技术相结合。作为这些发现的结果，我们建议，SinI利用残基置换机制，以阻止SinR多聚化，从而减少DNA结合和随之而来的阻遏活性降低。最后，我们提供了一个以证据为基础的机制，证实了SinI如何破坏SinR四聚体调节基因表达。(C)2019爱思唯尔有限公司版权所有。
Bacteria have developed numerous protection strategies to ensure survival in harsh environments, with perhaps the most robust method being the formation of a protective biofilm. In biofilms, bacterial cells are embedded within a matrix that is composed of a complex mixture of polysaccharides, proteins, and DNA. The gram-positive bacterium Bacillus subtilis has become a model organism for studying regulatory networks directing biofilm formation. The phenotypic transition from a planktonic to biofilm state is regulated by the activity of the transcriptional repressor, SinR, and its inactivation by its primary antagonist, SinI. In this work, we present the first full-length structural model of tetrameric SinR using a hybrid approach combining high-resolution solution nuclear magnetic resonance (NMR), chemical cross-linking, mass spectrometry, and molecular docking. We also present the solution NMR structure of the antagonist SinI dimer and probe the mechanism behind the SinR-SinI interaction using a combination of biochemical and biophysical techniques. As a result of these findings, we propose that SinI utilizes a residue replacement mechanism to block SinR multimerization, resulting in diminished DNA binding and concomitant decreased repressor activity. Finally, we provide an evidence-based mechanism that confirms how disruption of the SinR tetramer by SinI regulates gene expression. (C) 2019 Elsevier Ltd. All rights reserved.