Shi Haoyuan, Fu Yu, Kodyte Vilmante, Andreas Amelie, Sachla Ankita J, Miller Keikilani, Shrestha Ritu, Helmann John D, Glasfeld Arthur, Ahuja Shivani
Department of Chemistry, Reed College, Portland, Oregon, USA.
Department of Microbiology, Cornell University, Ithaca, NY, USA.
Nat Commun. 2025 Mar 5;16(1):2204. doi: 10.1038/s41467-025-57412-6.
Bacillus subtilis MntR is a dual regulatory protein that responds to heightened Mn availability in the cell by both repressing the expression of uptake transporters and activating the expression of efflux proteins. Recent work indicates that, in its role as an activator, MntR binds several sites upstream of the genes encoding Mn exporters, leading to a cooperative response to manganese. Here, we use cryo-EM to explore the molecular basis of gene activation by MntR and report a structure of four MntR dimers bound to four 18-base pair sites across an 84-base pair regulatory region of the mneP promoter. Our structures, along with solution studies including mass photometry and in vivo transcription assays, reveal that MntR dimers employ polar and non-polar contacts to bind cooperatively to an array of low-affinity DNA-binding sites. These results reveal the molecular basis for cooperativity in the activation of manganese efflux.
枯草芽孢杆菌MntR是一种双重调节蛋白，它通过抑制摄取转运蛋白的表达和激活外排蛋白的表达来响应细胞内锰可用性的提高。最近的研究表明，作为激活剂，MntR结合在编码锰外排蛋白的基因上游的几个位点，从而对锰产生协同反应。在这里，我们使用冷冻电镜来探索MntR激活基因的分子基础，并报告了四个MntR二聚体与跨越mneP启动子84个碱基对调控区域的四个18个碱基对位点结合的结构。我们的结构，以及包括质量光度法和体内转录分析在内的溶液研究表明，MntR二聚体利用极性和非极性接触来协同结合一系列低亲和力的DNA结合位点。这些结果揭示了锰外排激活中协同作用的分子基础。
