|
 |
|
|
| The EMBO Journal
(1998) 17, 2894–2903, doi:10.1093/emboj/17.10.2894 |
|
| Induction of type III secretion in Shigella flexneri is associated with differential control of transcription of genes encoding secreted proteins |
|
|
| Brigitte Demers, Philippe J. Sansonetti and Claude Parsot |
|
|
Unité de Pathogénie Microbienne Moléculaire and Unité INSERM U389, Institut Pasteur, 25 rue du Dr Roux, F-75724 Paris Cédex 15, France To whom correspondence should be addressed Brigitte Demers, bdemers@pasteur.fr Received 28 October 1997; Revised 18 February 1998; Accepted 16 March 1998. |
|
|
|
| Abstract |
|
| Shigella, the etiological agent of human bacillary dysentery, invades the colonic epithelium where it induces an intense inflammatory response. Entry of Shigella into epithelial cells involves a type III secretion machinery, encoded by the mxi and spa operons, and the IpaA–D secreted proteins. In this study, we have identified secreted proteins of 46 and 60 kDa as the products of virA and ipaH9.8, respectively, the latter being a member of the ipaH multigene family. Inactivation of virA did not affect entry into epithelial cells. Using lacZ transcriptional fusions, we found that transcription of virA and four ipaH genes, but not that of the ipaBCDA and mxi operons, was markedly increased during growth in the presence of Congo red and in an ipaD mutant, two conditions in which secretion through the Mxi–Spa machinery is enhanced. Transcription of the virA and ipaH genes was also transiently activated upon entry into epithelial cells. These results suggest that transcription of the virA and ipaH genes is regulated by the type III secretion machinery and that a regulatory cascade differentially controls transcription of genes encoding secreted proteins, some of which, like virA, are not required for entry. |
|
| Keywords: intracellular, invasion, pathogenesis, regulation, secretion |
|
|
| |
| |
| |
 | Email link to a friend |
| |
 | Download PDF |
| |
 | Full text |
| |
| |
| |
 | Next article |
| |
 | Previous article |
| |
 | Table of contents |
| |
| |
 | Rights and permissions |
| |
 | Reprints |
| |
| |
| |
 Register for table of contents by email | |
| |
| |
| |