Quasi-adaptive response to alkylating agents and Ada-protein functions in Escherichia coli

Abstract

In the exponentially growing E. coli cells we have described in 2005 a new fundamental genetic phenomenon, namely quasi-adaptive response to alkylating compounds, “quasi-Ada”. Phenotypic expression of “quasi-Ada” is similar to the true Ada response, however in contrast it develops in the course of pretreatment of the cells by sublethal dose of non-alkylating agent, an NO-containing dinitrosyl iron complex with glutathione (DNICglu). To reveal the mechanisms of quasi-adaptation and its association with the function of the regulatory protein Ada here we used a unique property of dual gene expression regulation of aidB1 gene, a part of Ada-regulon, namely its relative independence from Ada protein in anaerobic conditions. Based on the results of aidB1 gene expression analysis an EPR spectra of E.coli MV2176 cells (aidB1::lacZ) in aerobic and anaerobic conditions after the corresponding treatments we concluded that the function and the spatial structure of meAda and [(Cys−)2Fe+(NO+)2]Ada are identical and thus the nitrosylated protein represents an Ada regulon genes expression regulator during quasi-adaptation development.