Structural basis of dual activation of cell division by the actinobacterial transcription factors WhiA and WhiB.
Structural basis of dual activation of cell division by the actinobacterial transcription factors WhiA and WhiB.
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DOI：
10.1073/pnas.2220785120
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发表时间：
2023-03-14
影响因子：
11.1
通讯作者：
Campbell, Elizabeth A.
中科院分区：
文献类型：
--
作者：
Lilic, Mirjana;Holmes, Neil A.;Bush, Matthew J.;Marti, Alexandra K.;Widdick, David A.;Findlay, Kim C.;Choi, Young Joo;Froom, Ruby;Koh, Steven;Buttner, Mark J.;Campbell, Elizabeth A.
这项工作提供了独特的见解的进化和功能的两个非常不寻常的转录因子，WhiA和WhiB，控制孢子形成分隔产芽孢杆菌链霉菌。此外，在密切相关的病原体结核分枝杆菌（Mt B）中，WhiA和WhiB是必需的，因为它们是细胞分裂所需的，并且WhiA和WhiB中的突变在Mt B的临床分离株中被积极选择，这暗示WhiA/B在毒力和/或对药物治疗的抗性中。因此，我们的工作将提供功能洞察一类新的转录因子的分子机制，在一个重要的细菌分支，包含主要的抗生素生产商，同时通知的适应性WhiA/B突变的毒力和抗生素耐药性在致命的病原体。在不同的细菌分支的转录起始的研究揭示了不同的分子机制，调节基因表达的第一步。WhiA和WhiB因子都是放线菌中表达细胞分裂基因所必需的，并且在著名的病原体如结核分枝杆菌中是必需的。WhiA/B调节子和结合位点已在委内瑞拉链霉菌（Sven）中阐明，它们在其中协调以激活孢子形成分隔。然而，这些因素如何在分子水平上合作尚不清楚。在这里，我们提出了Sven转录调控复合物的冷冻电子显微镜结构，包括RNA聚合酶（RNAP）σ A全酶和WhiA和WhiB，与WhiA/B靶启动子sepX复合。这些结构表明WhiB与σ A全酶的σA结构域4（σA4）结合，桥接与WhiA的相互作用，同时与−35核心启动子元件上游的DNA进行非特异性接触。WhiA的N-末端归巢核酸内切酶样结构域与WhiB相互作用，而WhiA C-末端结构域（WhiA-CTD）与保守的WhiA GACAC基序进行碱基特异性接触。值得注意的是，WhiA-CTD的结构及其与WhiA基序的相互作用与σA4管家σ因子和−35启动子元件之间观察到的结构惊人地相似，表明了进化关系。旨在破坏这些蛋白质-DNA相互作用的结构指导的诱变减少或消除了Sven中的发育细胞分裂，证实了它们的重要性。最后，我们比较了WhiA/B σ A-全酶启动子复合物与不相关但模型CAP I类和II类复合物的结构，表明WhiA/WhiB代表细菌转录激活的新机制。
This work provides unique insight into the evolution and function of two highly unusual transcription factors, WhiA and WhiB, which control sporulation septation in the antibiotic-producing bacteria Streptomyces. Furthermore, in the closely related pathogen Mycobacterium tuberculosis (Mtb), WhiA and WhiB are essential because they are required for cell division, and mutations in whiA and whiB are positively selected in clinical isolates of Mtb, implicating WhiA/B in virulence and/or resistance to drug treatment. Our work will thus provide functional insight into the molecular mechanism of a new class of transcription factors in an important bacterial clade that contains the major antibiotic producers while informing on the adaptive nature of WhiA/B mutations in virulence and antibiotic resistance in a deadly pathogen. Studies of transcriptional initiation in different bacterial clades reveal diverse molecular mechanisms regulating this first step in gene expression. The WhiA and WhiB factors are both required to express cell division genes in Actinobacteria and are essential in notable pathogens such as Mycobacterium tuberculosis. The WhiA/B regulons and binding sites have been elucidated in Streptomyces venezuelae (Sven), where they coordinate to activate sporulation septation. However, how these factors cooperate at the molecular level is not understood. Here we present cryoelectron microscopy structures of Sven transcriptional regulatory complexes comprising RNA polymerase (RNAP) σA-holoenzyme and WhiA and WhiB, in complex with the WhiA/B target promoter sepX. These structures reveal that WhiB binds to domain 4 of σA (σA4) of the σA-holoenzyme, bridging an interaction with WhiA while making non-specific contacts with the DNA upstream of the −35 core promoter element. The N-terminal homing endonuclease-like domain of WhiA interacts with WhiB, while the WhiA C-terminal domain (WhiA-CTD) makes base-specific contacts with the conserved WhiA GACAC motif. Notably, the structure of the WhiA-CTD and its interactions with the WhiA motif are strikingly similar to those observed between σA4 housekeeping σ-factors and the −35 promoter element, suggesting an evolutionary relationship. Structure-guided mutagenesis designed to disrupt these protein–DNA interactions reduces or abolishes developmental cell division in Sven, confirming their significance. Finally, we compare the architecture of the WhiA/B σA-holoenzyme promoter complex with the unrelated but model CAP Class I and Class II complexes, showing that WhiA/WhiB represent a new mechanism in bacterial transcriptional activation.
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影响因子：
6.4
作者：
Bush MJ;Bibb MJ;Chandra G;Findlay KC;Buttner MJ
通讯作者：
Buttner MJ
影响因子：
6.4
作者：
DeJesus MA;Gerrick ER;Xu W;Park SW;Long JE;Boutte CC;Rubin EJ;Schnappinger D;Ehrt S;Fortune SM;Sassetti CM;Ioerger TR
通讯作者：
Ioerger TR
影响因子：
3.6
作者：
Bush MJ;Chandra G;Findlay KC;Buttner MJ
通讯作者：
Buttner MJ
影响因子：
64.8
作者：
BURGESS, RR;TRAVERS, AA;BAUTZ, EKF
通讯作者：
BAUTZ, EKF
细菌中转录起始的多样化且统一的机制。
DOI：
10.1038/s41579-020-00450-2
发表时间：
2021-03
期刊：
Nature reviews. Microbiology
影响因子：
--
作者：
Chen J;Boyaci H;Campbell EA
通讯作者：
Campbell EA