The Bacteroides thetaiotaomicron protein bacteroides host factor A participates in integration of the integrative conjugative element CTnDOT into the chromosome

CTnDOT is a conjugative transposon found in Bacteroides species. It encodes multiple antibiotic resistances and is stimulated to transfer by exposure to tetracycline. CTnDOT integration into the host chromosome requires IntDOT and a previously unknown host factor. We have identified a protein, designated BHFa (Bacteroides host factor A), that participates in integrative recombination. BHFa is the first host factor identified for a site-specific recombination reaction in the CTnDOT family of integrative and conjugative elements. Based on the amino acid sequence of BHFa, the ability to bind specifically to 4 sites in the attDOT DNA, and its activity in the integration reaction, BHFa is a member of the IHF/HU family of nucleoid-associated proteins. Other DNA bending proteins that bind DNA nonspecifically can substitute for BHFa in the integration reaction.