He Xiaoyuan, Wang Liqin, Wang Shuishu
Department of Biochemistry &Molecular Biology, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, Maryland 20814, USA.
Sci Rep. 2016 Apr 15;6:24442. doi: 10.1038/srep24442.
The transcriptional regulator PhoP is an essential virulence factor in Mycobacterium tuberculosis, and it presents a target for the development of new anti-tuberculosis drugs and attenuated tuberculosis vaccine strains. PhoP binds to DNA as a highly cooperative dimer by recognizing direct repeats of 7-bp motifs with a 4-bp spacer. To elucidate the PhoP-DNA binding mechanism, we determined the crystal structure of the PhoP-DNA complex. The structure revealed a tandem PhoP dimer that bound to the direct repeat. The surprising tandem arrangement of the receiver domains allowed the four domains of the PhoP dimer to form a compact structure, accounting for the strict requirement of a 4-bp spacer and the highly cooperative binding of the dimer. The PhoP-DNA interactions exclusively involved the effector domain. The sequence-recognition helix made contact with the bases of the 7-bp motif in the major groove, and the wing interacted with the adjacent minor groove. The structure provides a starting point for the elucidation of the mechanism by which PhoP regulates the virulence of M. tuberculosis and guides the design of screening platforms for PhoP inhibitors.
转录调节因子PhoP是结核分枝杆菌中一种至关重要的毒力因子，是开发新型抗结核药物和减毒结核疫苗菌株的靶点。PhoP通过识别带有4个碱基间隔的7个碱基基序的直接重复序列，以高度协同的二聚体形式与DNA结合。为阐明PhoP与DNA的结合机制，我们测定了PhoP-DNA复合物的晶体结构。该结构揭示了一个与直接重复序列结合的串联PhoP二聚体。受体结构域令人惊讶的串联排列使PhoP二聚体的四个结构域形成了一个紧凑的结构，这解释了对4个碱基间隔的严格要求以及二聚体的高度协同结合。PhoP与DNA的相互作用仅涉及效应结构域。序列识别螺旋与大沟中7个碱基基序的碱基接触，侧翼与相邻的小沟相互作用。该结构为阐明PhoP调节结核分枝杆菌毒力的机制提供了一个起点，并指导PhoP抑制剂筛选平台的设计。
