Role of DnaK in In Vitro and In Vivo Expression of Virulence Factors of Vibrio cholerae
IR@IICB: CSIR-Indian Institute of Chemical Biology, KolkataView Archive Info
Role of DnaK in In Vitro and In Vivo Expression of Virulence
Factors of Vibrio cholerae
Infectious Diseases and Immunology
The dnaK gene of Vibrio cholerae was cloned, sequenced, and used to construct a dnaK insertion mutant which
was then used to examine the role of DnaK in expression of the major virulence factors of this important
human pathogen. The central regulator of several virulence genes of V. cholerae is ToxR, a transmembrane
DNA binding protein. The V. cholerae dnaK mutant grown in standard laboratory medium exhibited phenotypes
characteristic of cells deficient in ToxR activity. Using Northern blot analysis and toxR transcriptional fusions,
we demonstrated a reduction in expression of the toxR gene in the dnaK mutant strain together with a
concomitant increase in expression of a htpG-like heat shock gene that is located immediately upstream and
is divergently transcribed from toxR. This may be due to increased heat shock induction in the dnaK mutant.
In vivo, however, although expression from heat shock promoters in the dnaK mutant was similar to that
observed in vitro, expression of both toxR and htpG was comparable to that by the parental strain. In both
strains, in vivo expression of toxR was significantly higher than that observed in vitro, but no reciprocal
decrease in htpG expression was observed. These results suggest that the modulation of toxR expression in vivo
may be different from that observed in vitro.
American Society for Microbiology
Chakrabarty, Sabyasachi and Sengupta, Nilanjan and Chowdhury, Rukhsana (1999) Role of DnaK in In Vitro and In Vivo Expression of Virulence Factors of Vibrio cholerae. Infection and Immunity, 67 (3). pp. 1025-1033.