Two-Dimensional Gel Electrophoresis Analysis of the Response of Pseudomonas putida KT2442 to 2-Chlorophenol.

The effects of exposure of Pseudomonas putida KT2442 to 2-chlorophenol as a model for the chemical stress response were examined by two-dimensional polyacrylamide gel electrophoresis. Individual protein concentrations were determined at 45, 65, and 95 min following the addition of 2-chlorophenol at a concentration of 1.63 mM to exponentially growing cultures of P. putida KT2442 by silver staining the separated proteins. The changes in the protein concentrations could be classified into four categories, namely those which increased continuously during exposure, those which decreased in concentration, those which showed a concentration peak at some point following exposure, and those which were essentially unaffected. Thirty proteins with isoelectric points between pH 4 and 6 increased in concentration, 27 decreased, and 90 had a concentration maximum or minimum between 45 and 95 min. Of those proteins with isoelectric points between 5.5 and 10, 68 increased in concentration, 39 decreased in concentration, and 47 showed a concentration peak in the middle of the sampling period. Thus, in the evaluation of the stress response, a functional description requires an understanding both of proteins which are required at higher concentrations and of those whose presence appears to be no longer essential.