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

In 2005 we have described in exponentially growing E. coli cells a new fundamental genetic phenomenon,--quasi-adaptive response to alkylating compounds (quasi-Ada). Phenotypic expression of quasi-Ada is similar to the true Ada response.

[The genetic activity of NO-containing agents is regulated by complex formation with intracellular iron].

This work is a part of a directional search for new crystal donors of nitric oxide (NO), which are promising for complex chemotherapy. The relationships between the physico-chemical properties of NO donors, their genotoxic and mutagenic activities, and the dependence on intracellular iron were studied. New crystal NO donors (di- and trinitrosyl iron complexes with synthetic ligands) were examined for the first time and compared with known NO donors containing natural ligands.

[O6-benzylguanine stimulates regulatory functions of the Ada protein in Escherichia coli].

In vitro experiments showed that O6-benzylguanine (O6-benzG, 0.2 microM) fully inhibited the repair activity of human O6-alkylguanine-DNA alkyltransferase (MGMT) due to the formation of S-benzylcytosine in the protein acceptor site. O6-benzG at concentrations increased many times (up to 800 microM) failed to inhibit the repair activity of the Escherichia coli Ada protein, the structural and functional analog of MGMT.

[Quasi-adaptive response to alkylating agents in Escherichia coli: a new phenomenon].

An original hypothesis of a quasi-adaptive response to nitrosomethylurea (NMU) in Escherichia coli cells was verified experimentally. In contrast to the true Ada response, which is induced in cells pretreated with a sublethal dose of NMU, a quasi-adaptive response was induced using NO-containing dinitrosyl iron complex with glutathione (DNICglu). Quasi-adaptation increased expression of the Ada regulon and cell resistance to the cytotoxic and mutagenic effects of NMU.

[Connectivity between soxS gene expression and adaptive resistance to the SoxRS-regulon inducers in E. coli cells].

Development of the adaptive response (AR) to the SoxRS-inducers-menadione (O2(-.)-donor), dinitrosyl-iron complex (NO donor) and their simultaneous action was studied in E. coli.