Purification and some properties of ATP-dependent deoxyribonuclease of Caulobacter crescentus

An ATP-dependent deoxyribonuclease has been partially purified from extracts of Caulobacter crescentus cells in a procedure involving ion-exchange and affinity chromatography. The enzyme was purified approximately 350-fold and was free of contaminating nucleolytic and ATPase activity. The nuclease hydrolyzes linear, double-stranded DNA with subsequent release of short oligonucleotides, mostly from one to four bases in length. The release of nucleotides is accompanied by hydrolysis of ATP, 7.6 nmol ATP being consumed for each nmol of acid-soluble products of DNA degradation. The enzyme shows an absolute requirement for divalent cations and is most active at pH 7.6 to 8.8. The molecular weight of the nuclease, estimated by gel filtration and sucrose density gradient centrifugation, is 280 000.