EXPRESSION OF DNAK AND GROEL HOMOLOGS IN LEUCONOSTOC ESENTEROIDES IN RESPONSE TO HEAT-SHOCK, COLD SHOCK OR CHEMICAL STRESS

The mechanism of adaptation of bacteria to survive at elevated tempera ture in the human host and the expression of heat-shock proteins in re sponse to stress was examined by labelling with [S-35]methionine. An i ncrease in culture temperature from 26 degrees C to 37 degrees C induc ed expression of certain bacterial proteins (70 and 60 kDa). Heat shoc k at 40 degrees C, cold shock (10 degrees C), ethanol treatment or ars enite treatment also led to an increased expression of heat shock prot eins of 70 and 60 kDa. Actinomycin D completely blocked the induction, indicating that transcription is required for the overexpression of s tress proteins in Leuconostoc mesenteroides. N-terminal sequence analy sis showed that these proteins were homologous to the highly conserved chaperone proteins DnaK and GroEL of Escherichia coli, respectively.