Characterization of the Vibrio cholerae ToxR regulon: identification of novel genes involved in intestinal colonization.

نویسندگان

  • K M Peterson
  • J J Mekalanos
چکیده

A gene fusion library of Vibrio cholerae classical strain O395 was generated by using a broad host range vector for delivery of the transposon TnphoA. The insertion library was screened for colonies expressing alkaline phosphatase-positive (PhoA+) fusion proteins on LB agar at 30 degrees C in the presence of 0.2% glucose. Over 600 PhoA+ strains were isolated and then tested for regulation of their gene fusions in broth media that permitted high or low expression of cholera toxin. This strategy resulted in the isolation of 60 TnphoA (Tn5 IS50L::phoA) fusions to genes encoding secreted proteins that are apparently coordinately regulated with cholera toxin. Introduction of a toxR null mutation into 10 of these fusion strains confirmed that these TnphoA gene fusions are controlled either directly or indirectly by the cholera toxin transcriptional activator encoded by toxR. A combination of Southern and immunoblot analysis identified 17 distinct ToxR-regulated genes in V. cholerae O395. Many of these insertions were located in one of the two cholera toxin operon copies of strain O395, as well as a large gene cluster involved in the biogenesis of the toxin-coregulated pilus colonization factor. In addition, insertions were identified in genes that had no effect on either cholera toxin or toxin-coregulated pilus expression. Several of these insertions were localized to a cluster of four genes, the disruption of any of which by TnphoA reduced the ability of strain O395 to colonize the intestines of suckling mice. The product encoded by this second gene cluster was named accessory colonization factor to describe its possible role in cholera pathogenesis. These studies reinforce the contribution of ToxR-regulated genes to the virulence properties of V. cholerae. This report also demonstrates a new approach for the identification of bacterial virulence factors, based on the characterization of genes that are regulated by the same environmental signals that control the expression of a known virulence factor.

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

منابع مشابه

The Vibrio cholerae ToxR Regulon Encodes Host-Specific Chemotaxis Proteins that Function in Intestinal Colonization.

Virulence gene regulation in Vibrio cholerae is under the control of the ToxR-ToxT regulatory cascade. Chemotaxis and net motility have been shown to influence the infectivity of Vibrio cholerae. V. cholerae toxR mutants do not synthesize proteins required for chemotaxis towards mucus. The inability of the toxR mutant strain to recognize and swim towards mucus is due to their failure to synthes...

متن کامل

A branch in the ToxR regulatory cascade of Vibrio cholerae revealed by characterization of toxT mutant strains.

Co-ordinate expression of genes associated with pathogenicity in Vibrio cholerae requires two transcription activators, ToxR and ToxT. Work carried out to date suggests that ToxR activates transcription of the toxT gene and that ToxT directly activates transcription of several genes whose products play a role in colonization or CT production by V. cholerae. Previous work also suggests that ToxR...

متن کامل

Quorum-sensing regulators control virulence gene expression in Vibrio cholerae.

The production of virulence factors including cholera toxin and the toxin-coregulated pilus in the human pathogen Vibrio cholerae is strongly influenced by environmental conditions. The well-characterized ToxR signal transduction cascade is responsible for sensing and integrating the environmental information and controlling the virulence regulon. We show here that, in addition to the known com...

متن کامل

Toxin, toxin-coregulated pili, and the toxR regulon are essential for Vibrio cholerae pathogenesis in humans

Isogenic mutant strains of V. cholerae O1 lacking elements of a genetic regulon controlled by toxR and implicated in virulence were tested in volunteers. A deletion mutation in ctxA, the gene encoding the A subunit of cholera toxin, markedly attenuated disease symptoms without affecting intestinal colonization. Deletion of toxR, the gene encoding the cholera toxin-positive regulatory protein re...

متن کامل

Co-ordinate expression of virulence genes by ToxR in Vibrio cholerae.

Evolution of complex regulatory pathways that control virulence factor expression in pathogenic bacteria indicates the importance to these organisms of being able to distinguish time and place. In the human intestinal pathogen Vibrio cholerae, control over many virulence genes identified to date is the responsibility of the ToxR protein. ToxR, in conjunction with a second regulatory protein cal...

متن کامل

ذخیره در منابع من


  با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

عنوان ژورنال:
  • Infection and immunity

دوره 56 11  شماره 

صفحات  -

تاریخ انتشار 1988