Abstract：
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.
摘要：
细菌接合是DNA从供体细胞单向转移至受体细胞的过程。它是抗生素抗性基因在细菌种群中传播的主要手段。它关键取决于细胞外附件的形成，称为“菌毛，“通过称为共轭的”IV型分泌系统的大型跨膜分泌系统。“在这里，我们介绍了由R388质粒编码的接合菌毛的结构。我们证明，与迄今为止用于低温电子显微镜（cryo-EM）结构测定的所有共轭菌毛相反，受体细胞的存在极大地刺激了R388质粒编码的接合菌毛。将其冷冻EM结构与现有的共轭菌毛结构进行比较，突出了R388菌毛结构与其同系物之间的许多重要差异，最突出的是其结合脂质的高度独特的构象。
