The excision proteins of CTnDOT positively regulate the transfer operon

Carolyn M. Keeton, Jiyeon Park, Gui Rong Wang, Crystal M. Hopp, Nadja B. Shoemaker, Jeffrey F. Gardner, Abigail A. Salyers

Research output: Contribution to journalArticlepeer-review


The Bacteroides conjugative transposon, CTnDOT, is an integrated conjugative element (ICE), found in many human colonic Bacteroides spp. strains. It has a complex regulatory system for both excision from the chromosome and transfer and mobilization into a new host. It was previously shown that a cloned DNA segment encoding the xis2c, xis2d, orf3, and exc genes was required for tetracycline dependent activation of the Ptra promoter. The Xis2c and Xis2d proteins are required for excision while the Exc protein stimulates excision. We report here that neither the Orf3 nor the Exc proteins are involved in activation of the Ptra promoter. Deletion analysis and electromobility shift assays showed that the Xis2c and Xis2d proteins bind to the Ptra promoter to activate the tra operon. Thus, the recombination directionality factors of CTnDOT excision also function as activator proteins of the Ptra promoter.

Original languageEnglish (US)
Pages (from-to)172-179
Number of pages8
Issue number2
StatePublished - Mar 2013


  • Bacteroides
  • CTnDOT
  • Exc
  • Gene regulation
  • Xis2c
  • Xis2d

ASJC Scopus subject areas

  • Molecular Biology


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