Department of Microbiology, Monash University, Clayton, 3168 Victoria, Australia.
A dual transcriptional activation system for the 230 kb plasmid genes coding for virulence-associated antigens of Shigella flexneri
Article first published online: 27 OCT 2006
Volume 3, Issue 5, pages 627–635, May 1989
How to Cite
Adler, B., Sasakawa, C., Tobe, T., Makino, S., Komatsu, K. and Yoshikawa, M. (1989), A dual transcriptional activation system for the 230 kb plasmid genes coding for virulence-associated antigens of Shigella flexneri. Molecular Microbiology, 3: 627–635. doi: 10.1111/j.1365-2958.1989.tb00210.x
- Issue published online: 27 OCT 2006
- Article first published online: 27 OCT 2006
- Received 29 November, 1988; revised 10 January, 1989.
The expression of plasmid-encoded, invasion-related antigens lpa b, c and d of Shigella flexneri was found to be positively regulated at transcriptional level by a 33kD protein produced by the previously defined, virulence-associated Region 1 on the SalI fragment B of the 230 kb invasion plasmid. The gene (designated virB) was identified and its nucleotide sequence determined. No Ipa b or c was produced in the absence of an intact virB gene although lower levels of d were produced. The previously reported regulatory activity of the virF gene some 30 kb distance away was shown to act exclusively through virB. In contrast, the activation of the virG gene necessary for intercellular spread occurred directly by virF without the requirement for virB. This study thus ascribes a critical function to a previously recognized, but functionally undefined, virulence locus on the large invasion plasmid of S. flexneri. The virF gene appears to have a central role in activation of the 230kb plasmid-encoded virulence genes.