Intrinsic apurinic/apyrimidinic (AP) endonuclease activity enables Bacillus subtilis DNA polymerase X to recognize, incise, and further repair abasic sites

摘要

The N-glycosidic bond can be hydrolyzed spontaneously or by\udglycosylases during removal of damaged bases by the base excision\udrepair pathway, leading to the formation of highly mutagenic\udapurinic/apyrimidinic (AP) sites. Organisms encode for evolutionarily\udconserved repair machinery, including specific AP endonucleases\udthat cleave the DNA backbone 5′ to the AP site to prime\udfurther DNA repair synthesis. We report on the DNA polymerase\udX from the bacteriumBacillus subtilis (PolXBs) that, along with polymerization\udand 3′–5′-exonuclease activities, possesses an intrinsic\udAP-endonuclease activity. Both, AP-endonuclease and 3′–5′-exonuclease\udactivities are genetically linked and governed by the same\udmetal ligands located at the C-terminal polymerase and histidinol\udphosphatase domain of the polymerase. The different catalytic\udfunctions of PolXBs enable it to perform recognition and incision\udat an AP site and further restoration (repair) of the original nucleotide\udin a standalone AP-endonuclease-independent way.