TcpA, an FtsK/SpoIIIE homolog, is essential for transfer of the conjugative plasmid pCW3 in Clostridium perfringens

Jennifer Anne Parsons, Trudi Leanne Bannam, Rodney James Devenish, Julian Ian Rood

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The conjugative tetracycline resistance plasmid pCW3 is the paradigm conjugative plasmid in the anaerobic Gram positive pathogen Clostridium perfringens. Two closely related FtsK/SpoIIIE homologs, TcpA and TcpB, are encoded on pCW3, which is significant since FtsK domains are found in coupling proteins of Gram negative conjugation systems. To develop an understanding of the mechanism of conjugative transfer in C. perfringens, we have determined the role of these proteins in the conjugation process. Mutation and complementation analysis was used to show that the tcpA gene was essential for the conjugative transfer of pCW3 and that the tcpB gene was not required for transfer. Furthermore, complementation of a pCW3 tcpA mutant with divergent tcpA homologs provided experimental evidence that all of the known conjugative plasmids from C. perfringens use a similar transfer mechanism. Functional genetic analysis of the TcpA protein established the essential role in conjugative transfer of its Walker A and Walker B ATP binding motifs and its FtsK-like RAAG motif. It is postulated that TcpA is the essential DNA translocase or coupling protein encoded by pCW3 and as such represents a key component of the unique conjugation process in C. perfringens.
Original languageEnglish
Pages (from-to)7782 - 7790
Number of pages9
JournalJournal of Bacteriology
Issue number21
Publication statusPublished - 2007

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