Department of Biochemistry and Molecular Biology and the Centre for Blood Research, University of British Columbia, Vancouver, BC, Canada.
Pathogen Molecular Genetics Section, Laboratory of Bacteriology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA.
Sci Adv. 2020 Sep 30;6(40). doi: 10.1126/sciadv.abb8219. Print 2020 Sep.
is a major human pathogen that has acquired alarming broad-spectrum antibiotic resistance. One group of secreted toxins with key roles during infection is the phenol-soluble modulins (PSMs). PSMs are amphipathic, membrane-destructive cytolytic peptides that are exported to the host-cell environment by a designated adenosine 5'-triphosphate (ATP)-binding cassette (ABC) transporter, the PSM transporter (PmtABCD). Here, we demonstrate that the minimal Pmt unit necessary for PSM export is PmtCD and provide its first atomic characterization by single-particle cryo-EM and x-ray crystallography. We have captured the transporter in the ATP-bound state at near atomic resolution, revealing a type II ABC exporter fold, with an additional cytosolic domain. Comparison to a lower-resolution nucleotide-free map displaying an "open" conformation and putative hydrophobic inner chamber of a size able to accommodate the binding of two PSM peptides provides mechanistic insight and sets the foundation for therapeutic design.
是一种主要的人类病原体，已经获得了令人震惊的广谱抗生素耐药性。在感染过程中具有关键作用的一组分泌毒素是酚溶性调节素（PSMs）。PSMs 是两亲性、破坏膜的细胞溶解性细胞毒素肽，由特定的腺苷 5'-三磷酸（ATP）结合盒（ABC）转运蛋白，即 PSM 转运蛋白（PmtABCD）输出到宿主细胞环境中。在这里，我们证明了 PSM 输出所需的最小 Pmt 单元是 PmtCD，并通过单颗粒冷冻电镜和 X 射线晶体学对其进行了首次原子特征描述。我们以接近原子分辨率捕获了处于 ATP 结合状态的转运蛋白，揭示了一种 II 型 ABC 外排器折叠结构，带有一个额外的细胞质结构域。与显示“开放”构象和可能容纳两个 PSM 肽结合的大小的假定疏水性内部腔的较低分辨率无核苷酸图谱进行比较，提供了机制见解，并为治疗设计奠定了基础。
