Abstract
Virulent bacteria of the genus Yersinia secrete a number of virulence determinants called Yops. These proteins lack typical signal sequences and are not posttranslationally processed. Two gene loci have been identified as being involved in the specific Yop secretion system (G. Cornelis, p. 231-265, In C. E. Hormache, C. W. Penn, and C. J. Smythe, ed., Molecular Biology of Bacterial Infection, 1992; S. C. Straley, G. V. Plano, E. Skrzypek, P. L. Haddix, and K. A. Fields, Mol. Microbiol. 8:1005-1010, 1993). Here, we have shown that the lcrB/virB locus (yscN to yscU) encodes gene products essential for Yop secretion. As in previously described secretion apparatus mutants, expression of the Yop proteins was decreased in the yscN/U mutants. An lcrH yscR double mutant expressed the Yops at an increased level but did not secrete Yops into the culture supernatant. The block in Yop expression of the ysc mutants was also circumvented by overexpression of the activator LcrF in trans. Although the Yops were expressed in elevated amounts, the Yops were still not exported. This analysis showed that the ysc mutants were unable to secrete Yops and that they were also affected in the negative Ca(2+)-regulated loop. The yscN/U genes showed remarkably high homology to the spa genes of Shigella flexneri and Salmonella typhimurium with respect to both individual genes and gene organization. These findings indicate that the genes originated from a common ancestor.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.