Multiple stressor-induced proteome responses of Escherichia coli BL21(DE3)

Through 2-DE based quantitative proteomics, the dynamic characteristics of overall proteome profiles of Escherichia coli BL21(DE3) were systematically analyzed in the presence of four different stressors. Dithiothreitol and 2-hydroxyethyl disulfide are a reducing and an oxidizing agent, respectively, which disturb the redox balance in cytoplasm, while guanidine hydrochloride and heat shock are protein denaturants influencing protein folding. Heat shock proteins/foldases, transcription/translation-related proteins, various metabolic enzymes, and other stress regulatory proteins were found to be significantly up-regulated in response to the stressors. Heat shock proteins and translation-related proteins were generally responsive to almost all stress conditions. Two stressors, oxidative stress and guanidine hydrochloride-derived protein denaturation commonly induced the up-regulation of proteins related to transcription, whereas metabolic enzymes showed stress responses especially to the treatment of guanidine hydrochloride and heat shock. Similarities and differences of stress responses and protein-protein interactions of 80 proteins were systematically compared, and of special note, proteome-based stress-responsive proteins identified in the present study included 26 proteins that are being reported for the first time. The quantitative and systematic proteome analyses that we have performed provide more detailed information on E. coli BL21(DE3), a widely used host strain for recombinant protein overexpression.