Lou Yuan-Chao, Weng Tsai-Hsuan, Li Yi-Chuan, Kao Yi-Fen, Lin Wei-Feng, Peng Hwei-Ling, Chou Shan-Ho, Hsiao Chwan-Deng, Chen Chinpan
Institute of Biomedical Sciences, Academia Sinica, Taipei 115, Taiwan, ROC.
Institute of Molecular Biology, Academia Sinica, Taipei 115, Taiwan, ROC.
Nat Commun. 2015 Nov 13;6:8838. doi: 10.1038/ncomms9838.
PmrA, an OmpR/PhoB family response regulator, manages genes for antibiotic resistance. Phosphorylation of OmpR/PhoB response regulator induces the formation of a symmetric dimer in the N-terminal receiver domain (REC), promoting two C-terminal DNA-binding domains (DBDs) to recognize promoter DNA to elicit adaptive responses. Recently, determination of the KdpE-DNA complex structure revealed an REC-DBD interface in the upstream protomer that may be necessary for transcription activation. Here, we report the 3.2-Å-resolution crystal structure of the PmrA-DNA complex, which reveals a similar yet different REC-DBD interface. However, NMR studies show that in the DNA-bound state, two domains tumble separately and an REC-DBD interaction is transiently populated in solution. Reporter gene analyses of PmrA variants with altered interface residues suggest that the interface is not crucial for supporting gene expression. We propose that REC-DBD interdomain dynamics and the DBD-DBD interface help PmrA interact with RNA polymerase holoenzyme to activate downstream gene transcription.
PmrA是一种OmpR/PhoB家族反应调节因子，负责调控抗生素抗性相关基因。OmpR/PhoB反应调节因子的磷酸化会在N端接收结构域（REC）诱导形成对称二聚体，促使两个C端DNA结合结构域（DBD）识别启动子DNA以引发适应性反应。最近，KdpE-DNA复合物结构的测定揭示了上游原体中的REC-DBD界面，这可能是转录激活所必需的。在此，我们报道了PmrA-DNA复合物的3.2 Å分辨率晶体结构，该结构揭示了一个相似但又不同的REC-DBD界面。然而，核磁共振研究表明，在DNA结合状态下，两个结构域各自翻转，并且在溶液中REC-DBD相互作用是短暂存在的。对界面残基改变的PmrA变体进行的报告基因分析表明，该界面对于支持基因表达并非至关重要。我们提出，REC-DBD结构域间的动力学以及DBD-DBD界面有助于PmrA与RNA聚合酶全酶相互作用，从而激活下游基因转录。
