Le Bas Audrey, Clarke Bradley R, Teelucksingh Tanisha, Lee Micah, El Omari Kamel, Giltrap Andrew M, McMahon Stephen A, Liu Hui, Beale John H, Mykhaylyk Vitaliy, Duman Ramona, Paterson Neil G, Ward Philip N, Harrison Peter J, Weckener Miriam, Pardon Els, Steyaert Jan, Liu Huanting, Quigley Andrew, Davis Benjamin G, Wagner Armin, Whitfield Chris, Naismith James H
Rosalind Franklin Institute, Harwell Campus, Didcot, UK.
Division of Structural Biology, University of Oxford, Roosevelt Drive, Oxford, UK.
Open Biol. 2025 Jan;15(1):240310. doi: 10.1098/rsob.240310. Epub 2025 Jan 8.
The enterobacterial common antigen (ECA) is conserved in Gram-negative bacteria of the order although its function is debated. ECA biogenesis depends on the Wzx/Wzy-dependent strategy whereby the newly synthesized lipid-linked repeat units, lipid III, are transferred across the inner membrane by the lipid III flippase WzxE. WzxE is part of the Wzx family and required in many glycan assembly systems, but an understanding of its molecular mechanism is hindered due to a lack of structural evidence. Here, we present the first X-ray structures of WzxE from in complex with nanobodies. Both inward- and outward-facing conformations highlight two pairs of arginine residues that move in a reciprocal fashion, enabling flipping. One of the arginine pairs coordinated to a glutamate residue is essential for activity along with the C-terminal arginine rich tail located close to the entrance of the lumen. This work helps understand the translocation mechanism of the Wzx flippase family.
肠杆菌共同抗原（ECA）在该菌目中的革兰氏阴性菌中是保守的，尽管其功能仍存在争议。ECA的生物合成依赖于Wzx/Wzy依赖性策略，即新合成的脂质连接重复单元脂质III通过脂质III翻转酶WzxE跨内膜转运。WzxE是Wzx家族的一部分，在许多聚糖组装系统中是必需的，但由于缺乏结构证据，对其分子机制的理解受到阻碍。在这里，我们展示了来自[具体来源]的WzxE与纳米抗体复合物的首个X射线结构。向内和向外的构象都突出了两对以相反方式移动的精氨酸残基，从而实现翻转。与谷氨酸残基配位的一对精氨酸以及靠近管腔入口的富含精氨酸的C末端尾巴对于活性至关重要。这项工作有助于理解Wzx翻转酶家族的转运机制。
