Isolation and Characterization of a Magnesium-Dependent Apurinic Sites Specific Endodeoxyribonuclease from Bacillus subtilis

Abstract

A new endodeoxyribonuclease specific to apurinic sites in DNA was purified from vegetative cells of Bacillus subtilis. The enzyme hydrolyzes a phosphodiester bond near the heatinduced apurinic sites in double or single strand DNA; it does not hydrolyze native nor alkylated DNA. The endonuclease has a molecular weight of around 105, 000 and consists of four identical subunits. The enzyme requires absolutely Mg²⁺ for its activity and is inhibited by EDTA. It is completely inhibited by 1M NaCl or 1mm p-chloromercurybenzoate.These properties are very different from those of the endonuclease specific to apurinic sites in DNA isolated from B. subtilis by Inoue and Kada and those of endonuclease IV and VI of Escherichia coli.