Amount and redox state of cytoplasmic, membrane and periplasmic proteins in Escherichia coli redox mutants

We analyzed the amount and redox state of cytoplasmic, membrane and peripla smic proteins in Escherichia coli mutants deficient in thioredoxin, thiored oxin reductase, glutathione and DsbA, by observing the electrophoretic prof ile of bacterial extracts after in vivo labelling with monobromobimane. Our results show that these mutations affected not only the amount and the red ox state of proteins localized in the same compartment as the deficient oxi doreductase. but also those of the proteins localized in other compartments . These results concord with the hypothesis that there is a link between th e redox reactions that occur in the cytoplasm and the periplasm. (C) 2001 E ditions scientifiques et medicales Elsevier SAS.