[Para-aminobenzoic acid intensification of DNA repair processes in Escherichia coli K-12]

Studies of the role of physiologically active natural compound, para-aminobenzoic acid (PABA) in genetic processes showed that PABA interacts with bacterial DNA and strongly increases the effectiveness of repair processes under the mutagenic action of NMU, NEU, MMS and EMS. These properties of PABA differentially depended on the activity of enzymatic systems fo DNA repair and were most pronounced in repair-proficient strains of Escherichia coli. For example, the cooperative action of E. coli (wild type) of both NMU and PABA led to enhanced viability (13-100 times higher) and decreased the rate of induced reversions (5-60 times lower), in comparison with mutagenic action of "pure" NMU. Therefore, the specific function of PABA was called "reparagenic" and PABA itself "reparagen". UV-spectroscopy and nuclear-magnetic resonance were used to have revealed that PABA does not interact with MMS and NMU in vitro and does not change the rate of the mutagen's hydrolysis. Used in a wide range of concentrations, PABA induces no mutations in bacterial cells and does not increase the rate of genetic recombination. The discovery of the role of PABA in repair process opens up the possibility of examining the interaction between the DNA in a complex with reparagen as well as the dominant and recessive genes of the repair process.