Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, NC 27695, USA; Department of Discovery Sciences, RTI International, 3040 E. Cornwallis Road, Research Triangle Park, NC 27709, USA.
Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, NC 27695, USA.
J Mol Biol. 2018 Mar 16;430(6):806-821. doi: 10.1016/j.jmb.2018.02.002. Epub 2018 Feb 10.
The rise of drug-resistant bacterial infections coupled with decreasing antibiotic efficacy poses a significant challenge to global health care. Acinetobacter baumannii is an insidious, emerging bacterial pathogen responsible for severe nosocomial infections aided by its ability to form biofilms. The response regulator BfmR, from the BfmR/S two-component system, is the master regulator of biofilm initiation in A. baumannii and is a tractable therapeutic target. Here we present the structure of A. baumannii BfmR using a hybrid approach combining X-ray crystallography, nuclear magnetic resonance spectroscopy, chemical crosslinking mass spectrometry, and molecular modeling. We also show that BfmR binds the previously proposed bfmRS promoter sequence with moderate affinity. While BfmR shares many traits with other OmpR/PhoB family response regulators, some unusual properties were observed. Most importantly, we observe that when phosphorylated, BfmR binds this promoter sequence with a lower affinity than when not phosphorylated. All other OmpR/PhoB family members studied to date show an increase in DNA-binding affinity upon phosphorylation. Understanding the structural and biochemical mechanisms of BfmR will aid in the development of new antimicrobial therapies.
耐药细菌感染的增加加上抗生素疗效的降低，对全球医疗保健构成了重大挑战。鲍曼不动杆菌是一种阴险的、新兴的细菌病原体，其形成生物膜的能力使其能够导致严重的医院获得性感染。来自 BfmR/S 双组分系统的响应调节剂 BfmR 是鲍曼不动杆菌生物膜起始的主要调节剂，是一个可行的治疗靶点。在这里，我们使用结合 X 射线晶体学、核磁共振波谱学、化学交联质谱和分子建模的混合方法来呈现鲍曼不动杆菌 BfmR 的结构。我们还表明，BfmR 以中等亲和力结合先前提出的 bfmRS 启动子序列。虽然 BfmR 与其他 OmpR/PhoB 家族响应调节剂有许多共同特征，但也观察到了一些不寻常的特性。最重要的是，我们观察到当被磷酸化时，BfmR 与该启动子序列的结合亲和力低于未磷酸化时的结合亲和力。迄今为止研究过的所有其他 OmpR/PhoB 家族成员在磷酸化后都显示出 DNA 结合亲和力的增加。了解 BfmR 的结构和生化机制将有助于开发新的抗菌治疗方法。
