GLOBAL RESPONSE OF ESCHERICHIA-COLI-CELLS TO A TREATMENT WITH 7-METHOXY-2-NITRONAPHTHO[2,1-B]FURAN (R7000), AN EXTREMELY POTENT MUTAGEN

We have studied the global changes which are induced in exponentially growing cultures of Escherichia coli during treatment with 7-methoxy-2 -nitronaphtho[2,1-b]furan (R7000), a very potent mutagen and inducer o f the SOS response. A two-dimensional analysis of the proteins synthes ized in the presence of this agent was performed. In a strain deficien t in SOS induction, the expression of 24 polypeptides was found to be affected by this treatment: 14 corresponded to proteins known to be im plicated in different stress responses, particularly chaperones such a s DnaK and GroEL. The variation of another protein was detected for th e first time in this study: transketolase I, an enzyme of intermediary metabolism which was characterized in the present work by microsequen cing. In parallel, the expression of 9 other proteins, still unidentif ied, was modified by this nitrofuran. They represent potential candida tes involved in metabolic and DNA lesions repair specific of R7000 act ion.