This Article Full Text Full Text (PDF) Other Versions of this Article: JB.00932-07v1 189/20/7254    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Lee, C. A. Articles by Grossman, A. D. Search for Related Content PubMed PubMed Citation Articles by Lee, C. A. Articles by Grossman, A. D.

Identification of the Origin of Transfer (oriT) and DNA Relaxase Required for Conjugation of the Integrative and Conjugative Element ICEBs1 of Bacillus subtilis

Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139

Received 13 June 2007/ Accepted 1 August 2007

Integrative and conjugative elements (ICEs), also known as conjugative transposons, are mobile genetic elements that can transfer from one bacterial cell to another by conjugation. ICEBs1 is integrated into the trnS-leu2 gene of Bacillus subtilis and is regulated by the SOS response and the RapI-PhrI cell-cell peptide signaling system. When B. subtilis senses DNA damage or high concentrations of potential mating partners that lack the element, ICEBs1 excises from the chromosome and can transfer to recipients. Bacterial conjugation usually requires a DNA relaxase that nicks an origin of transfer (oriT) on the conjugative element and initiates the 5'-to-3' transfer of one strand of the element into recipient cells. The ICEBs1 ydcR (nicK) gene product is homologous to the pT181 family of plasmid DNA relaxases. We found that transfer of ICEBs1 requires nicK and identified a cis-acting oriT that is also required for transfer. Expression of nicK leads to nicking of ICEBs1 between a GC-rich inverted repeat in oriT, and NicK was the only ICEBs1 gene product needed for nicking. NicK likely mediates conjugation of ICEBs1 by nicking at oriT and facilitating the translocation of a single strand of ICEBs1 DNA through a transmembrane conjugation pore.

Published ahead of print on 10 August 2007.

This article has been cited by other articles:

• Ceccarelli, D., Daccord, A., Rene, M., Burrus, V. (2008). Identification of the Origin of Transfer (oriT) and a New Gene Required for Mobilization of the SXT/R391 Family of Integrating Conjugative Elements. J. Bacteriol. 190: 5328-5338 [Abstract] [Full Text]