Induction of heat shock response in Vibrio cholerae

General properties of the heat shock response in Vibrio cholerae were examined. Enhanced or de novo synthesis of 24 proteins was observed upon heat shock from 30 degrees C to 42 degrees C in cells labelled with [35S]methionine. A similar response could also be induced by a rise in temperature from 30 degrees C to 37 degrees C. Of these heat shock proteins, two were determined to be homologues of GroEL and DnaK, based upon their immunological cross-reactivity with antibodies raised against the Escherichia coli proteins. Three proteins, of molecular sizes 38, 44 and 48 kDa, which were undetectable in the 30 degrees C grown culture, appeared de novo after the heat shock. As in other prokaryotic systems thermal induction of many of the proteins was transient, but both DnaK and GroEL remained induced for at least 28 min after heat shock. DNA hybridization studies revealed that genes analogous not only to dnaK and groEL but also to dnaJ of E. coli exist in V. cholerae. Heat shock induced thermotolerance in V. cholerae but made the cells more sensitive to UV radiation. Unlike in E. coli, however, heat shock had no effect on the progeny virus yield in V. cholerae.