Regulation of DNA phosphorothioate modification in Salmonella enterica by DndB.
Regulation of DNA phosphorothioate modification in Salmonella enterica by DndB.
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DndB 对肠道沙门氏菌 DNA 硫代磷酸酯修饰的调控
DOI：
10.1038/srep12368
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发表时间：
2015-07-20
影响因子：
4.6
通讯作者：
Wang L
中科院分区：
文献类型：
--
作者：
He W;Huang T;Tang Y;Liu Y;Wu X;Chen S;Chan W;Wang Y;Liu X;Chen S;Wang L
DNA硫代修饰，即糖-磷酸骨架上的非桥氧被硫取代，在不同的细菌和古菌中自然发生，并受DndABCDE蛋白的调节。DndABCDE和限制性同源基因DndFGHI构成了一种新型的防御系统，可以阻止外来DNA在Cerro 87肠杆菌中的入侵。跨基因组的GaAc/GTTC共识上下文被发现即使在限制活性存在的情况下也具有部分PT修改，表明PT的调节。必须控制细胞内PT的丰度，以适应细胞活动。然而，PT修饰的调控机制尚不清楚。结果表明，肠杆菌基因组PT的修饰是由转录调控因子DndB控制的，它与启动子上的两个区域结合，每个区域都有一个5‘-TACGN10CGTA-3’回文基序，以调节dndCDE及其自身基因的转录。定点突变表明，DnDB的Cys29残基对其DNA结合活性或构象起关键作用。蛋白质组学分析发现，在PT上调和丢失时，许多细胞蛋白质发生了变化。考虑到DND操纵子的遗传保守性，DnDB对PT的调节可能在不同的生物体中广泛存在。
DNA phosphorothioate (PT) modification, in which the non-bridging oxygen of the sugar-phosphate backbone is substituted by sulfur, occurs naturally in diverse bacteria and archaea and is regulated by the DndABCDE proteins. DndABCDE and the restriction cognate DndFGHI constitute a new type of defense system that prevents the invasion of foreign DNA in Salmonella enterica serovar Cerro 87. GAAC/GTTC consensus contexts across genomes were found to possess partial PT modifications even in the presence of restriction activity, indicating the regulation of PT. The abundance of PT in cells must be controlled to suit cellular activities. However, the regulatory mechanism of PT modification has not been characterized. The result here indicated that genomic PT modification in S. enterica is controlled by the transcriptional regulator DndB, which binds to two regions in the promoter, each possessing a 5′-TACGN10CGTA-3′ palindromic motif, to regulate the transcription of dndCDE and its own gene. Site-directed mutagenesis showed that the Cys29 residue of DndB plays a key role in its DNA-binding activity or conformation. Proteomic analysis identified changes to a number of cellular proteins upon up-regulation and loss of PT. Considering the genetic conservation of dnd operons, regulation of PT by DndB might be widespread in diverse organisms.