Institute of Structural and Molecular Biology, Department of Biological Sciences, Birkbeck College, Malet Street, London WC1E 7HX, UK.
Institute of Structural and Molecular Biology, Division of Biosciences, University College London, Gower Street, London WC1E 6BT, UK.
Structure. 2024 Sep 5;32(9):1335-1347.e5. doi: 10.1016/j.str.2024.06.009. Epub 2024 Jul 12.
Bacterial conjugation is a process by which DNA is transferred unidirectionally from a donor cell to a recipient cell. It is the main means by which antibiotic resistance genes spread among bacterial populations. It is crucially dependent upon the elaboration of an extracellular appendage, termed "pilus," by a large double-membrane-spanning secretion system termed conjugative "type IV secretion system." Here we present the structure of the conjugative pilus encoded by the R388 plasmid. We demonstrate that, as opposed to all conjugative pili produced so far for cryoelectron microscopy (cryo-EM) structure determination, the conjugative pilus encoded by the R388 plasmid is greatly stimulated by the presence of recipient cells. Comparison of its cryo-EM structure with existing conjugative pilus structures highlights a number of important differences between the R388 pilus structure and that of its homologs, the most prominent being the highly distinctive conformation of its bound lipid.
细菌接合是一种单向将 DNA 从供体细胞转移到受体细胞的过程。它是抗生素抗性基因在细菌种群中传播的主要方式。它极大地依赖于一个大型双膜跨越分泌系统——称为“共轭型 IV 型分泌系统”——产生的一种称为“菌毛”的细胞外附属物。在这里，我们展示了由 R388 质粒编码的共轭菌毛的结构。我们证明，与迄今为止为 cryo-EM 结构测定而产生的所有共轭菌毛不同，由 R388 质粒编码的共轭菌毛在受体细胞存在下受到极大的刺激。将其 cryo-EM 结构与现有的共轭菌毛结构进行比较，突出了 R388 菌毛结构与其同源物之间的一些重要差异，最显著的是其结合脂质的高度独特构象。
