AdeR–AdeS is a two-component regulatory system, which controls expression of the adeABC efflux pump involved in Acinetobacter baumannii multidrug resistance. AdeR is a response regulator consisting of an N-terminal receiver domain and a C-terminal DNA-binding-domain. AdeR binds to a direct-repeat DNA in the intercistronic region between adeR and adeABC. We demonstrate a markedly high affinity binding between unphosphorylated AdeR and DNA with a dissociation constant of 20 nM. In addition, we provide a 2.75 Å crystal structure of AdeR DNA-binding-domain complexed with the intercistronic DNA. This structure shows that the α3 and β hairpin formed by β5–β6 interacts with the major and minor groove of the DNA, which in turn leads to the introduction of a bend. The AdeR receiver domain structure revealed a dimerization motif mediated by a gearwheel-like structure involving the D108F109-R122 motif through cation π stack interaction. The structure of AdeR receiver domain bound with magnesium indicated a conserved Glu19Asp20-Asp63 magnesium-binding motif, and revealed that the potential phosphorylation site Asp63^OD1 forms a hydrogen bond with Lys112. We thus dissected the mechanism of how AdeR recognizes the intercistronic DNA, which leads to a diverse mode of response regulation. Unlocking the AdeRS mechanism provides ways to circumvent A. baumannii antibiotic resistance.

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关于多药耐药鲍曼不动杆菌反应调节剂AdeR如何识别顺反子区域的机制的见解

AdeR–AdeS是一个两组分的调节系统，它控制涉及鲍曼不动杆菌多药耐药性的adeABC外排泵的表达。AdeR是由N端受体结构域和C端DNA结合结构域组成的响应调节剂。AdeR与adeR和adeABC之间的顺反子区域中的直接重复DNA结合。我们证明了未磷酸化的AdeR和DNA之间的解离常数为20 nM的显着高亲和力结合。此外，我们提供了一个2.75ÅAdeR DNA结合结构域与顺反子间DNA复合的晶体结构。这种结构表明，由β5-β6形成的α3和β发夹与DNA的主要和次要凹槽相互作用，进而导致引入弯曲。AdeR受体域结构揭示了一个二聚化基序，该基团由包含D108F109-R122基序的齿轮状结构通过阳离子π堆栈相互作用介导。与镁结合的AdeR受体域的结构表明Glu19Asp20-Asp63镁结合保守的基序，并揭示了潜在的磷酸化位点Asp63 ^OD1与Lys112形成氢键 因此，我们解剖了AdeR如何识别顺反子间DNA的机制，从而导致了多种反应调节模式。解锁AdeRS机制提供了规避鲍曼不动杆菌抗生素耐药性的方法。