Conjugative DNA transfer is a major factor in the dissemination of antibiotic resistance and virulence genes. In the Gram-positive pathogen Clostridium perfringens, the majority of conjugative plasmids share the conserved tcp locus that governs the assembly of the transfer system. Here, we describe multiple structures of the coupling protein TcpA, an essential ATPase that is suggested to provide the mechanical force to propel the DNA through the transfer apparatus. The structures of TcpA in the presence and absence of nucleotides revealed conformational rearrangements and highlight a crucial role for the unstructured C terminus. Our findings reveal that TcpA shares most structural similarity with the FtsK DNA translocase, a central component of the bacterial cell division machinery. Our structural data suggest that conjugation in C. perfringens may have evolved from the bacterial chromosome segregation system and, accordingly, suggest the possibility that double-stranded DNA is transferred through the Tcp conjugation apparatus.

结合 DNA 转移是抗生素抗性和毒力基因传播的主要因素。在革兰氏阳性病原体产气荚膜梭菌中，大多数结合质粒共享保守的tcp控制传输系统组装的位点。在这里，我们描述了偶联蛋白 TcpA 的多种结构，这是一种必需的 ATP 酶，建议提供机械力以推动 DNA 通过转移装置。在核苷酸存在和不存在的情况下，TcpA 的结构揭示了构象重排，并突出了非结构化 C 末端的关键作用。我们的研究结果表明，TcpA 与 FtsK DNA 转位酶具有最大的结构相似性，FtsK DNA 转位酶是细菌细胞分裂机制的核心组成部分。我们的结构数据表明产气荚膜梭菌中的结合可能是从细菌染色体分离系统进化而来的，因此表明双链 DNA 可能通过 Tcp 结合装置转移。