Influence of chemical analogues of microbial autoregulators on the sensitivity of DNA to UV radiation

We established that chemical analogues of alkylhydroxybenzenes (AHB), belonging to alkylresorcinols and functioning as microbial autoregulatory d₁ factors, enhance the UV resistance of various DNA molecules of different origin and conformation. These include the linear DNA of the λ phage, bovine spleen DNA, and the DNA of the pUC19 plasmid that is composed of a number of annular (supercoiled and relaxed) and linearized molecules. Irradiating DNA with UV light (λ = 254 nm) in the presence of methylresorcinol (MR) or hexylresorcinol (HR) results in comparatively insignificant DNA destruction as evidenced by our data on the electrophoretic mobility pattern in agarose gel. Using the linear HindIII restricts of the λ phage DNA, we revealed that the protective effect of AHB varies depending on their chemical structure (it is more manifest with HR than MR) and the concentration. Importantly, the effect of HR on bovine spleen DNA was based on its protective activity and manifested itself after a long incubation period. Studies using the pUC19 plasmid demonstrated that AHB, apart from increasing the resistance of linearized DNA molecules to UV irradiation, prevented both the supercoiled annular-supercoiled relaxed and the supercoiled relaxed-linearized transitions. The possible mechanisms of the UV-protective effect of AHB on DNA and their contributions to the resistance of dormant microbial forms to environmental factors are discussed.