FtsK translocation permits discrimination between an endogenous and an imported Xer/ dif recombination complex
Résumé
Significance This study focuses on a molecular machine (Xer/ dif /FtsK) involved in circular chromosome processing during the bacterial cell cycle. Xer site-specific recombinases are well known to act at the chromosomal dif (dimer resolution) sites for chromosome dimer resolution (CDR). The Xer/ dif recombination machine is, however, highly versatile and is also implicated in integration and excision of mobile genetic elements (MGE). Whereas CDR depends on the FtsK DNA translocase, MGE mobility somehow escapes this control. Focusing on the case of the gonococcal genetic island found in pathogenic Neisseria species, we reveal how FtsK distinguishes a Xer/ dif complex involved in vertical genetic transfer (CDR) from one involved in horizontal gene transfer (MGE mobility).