Cloning expression and biochemical characterizations of 8-oxoguanine DNA glycosylase from Pyrococcus furiosus

Abstract:

[Objective] Express and purify the Pyrococcus furiosus (P. furiosus) 8-oxoguanine DNA glycosylase; characterize the enzymatic properties of the recombinant P. furiosus 8-oxoguanine DNA glycosylase. [Methods] First, pfogg gene was cloned into an expression vector. Second, the expression of the recombinant protein was induced in Escherichia coli Rosetta (DE3) by IPTG. Third, the recombinant protein was purified through Ni2+ affinity chromatography. Finally, the enzymatic reaction of PfOgg was biochemically characterized using different oligonucleotides as substrates. [Results] The recombinant P. furiosus 8-oxoguanine DNA glycosylase was successfully expressed in E. coli and the purity was up to 95%. The enzymatic characterizations of recombinant P. furiosus 8-oxoguanine DNA glycosylase were assayed in vitro. The results showed that (1) the recombinant P. furiosus 8-oxoguanine DNA glycosylase could efficiently remove the 8-oxoguanine damage from both single-stranded and double-stranded DNA and the excision efficiency of 8-oxoguanine from various DNA substrates was the following order: GO/C≈GO/G≈GO/T≈GO/A>GO/?; (2) the optimal pH value and temperature for the reaction were pH 8.5 and 55 °C, respectively; (3) Zn2+ clearly inhibited the removal of 8-oxo-G by PfOgg, and the other divalent ions, such as Mn2+, Mg2+, Ca2+, Ni2+, Co2+ and Cu2+ had no significant effect on the enzymatic reaction; (4) the removal of 8-oxo-G was highly efficient with the ionic strength ranging from 50 to 100 mmol/L, but was clearly inhibited by higher ionic strength (above 100 mmol/L). (5) the PfOgg is highly heat-resistant, with a half lifetime of 5 min at 100 °C. [Conclusion] P. furiosus 8-oxoguanine DNA glycosylase was successfully expressed in E. coli, and had the typical enzymatic activities of removing the 8-oxoguanine damaged base from single-stranded and double-stranded DNA.

Key words:Pyrococcus furiosus, 8-Oxoguanine DNA glycosylase, Base excision repair