Mechanism of Inhibition of Bacillus subtilis DNA Polymerase III by the Arylhydrazinopyrimidine Antimicrobial Agents

Arylhydrazinopyrimidines inhibit DNA synthesis in Bacillus subtilis by promoting formation of a specific, long-lived ternary complex with DNA polymerase III and the template-primer DNA. DNA polymerase III contains an associated, single-strand-selective exonuclease which generates 5‧-mononucleotides. Drug inhibition of the nuclease similarly proceeds through formation of the ternary complex. The ternary complex was isolated by agarose chromatography. Like inhibition of the nuclease, optimum formation of the complex requires duplex DNA with single-stranded regions such as bacteriophage λ DNA (purely single- and double-stranded DNA are ineffective) and is antagonized by specific deoxyribonucleoside triphosphates. Formation of the ternary complex requires a di- or polyvalent cation and is inhibited by sulfhydryl reagents and high ionic strength. The complex dissociates with a half-life of the order of minutes at 4°.