Turning on Protein Function Inhibited by DNA Aptamers Employing a Covalent DNA-Binding Protein

Certain DNA aptamers can serve as effective inhibitors, although their inhibitory action is typically unidirectional. Simple removal of these aptamers from their target complexes could improve their application in areas such as oligonucleotide therapeutics. In the current study, we used uracil-DNA glycosylase from Mycobacterium smegmatis (UdgX), which binds covalently to DNA after uracil removal. A suitable site for incorporating uracil-DNA into a G-quadruplex-structured DNA aptamer was identified, and subsequent restoration of thrombin activity previously inhibited by the DNA aptamers was examined. The addition of UdgX restored thrombin activity to nearly 100% within 1 min, demonstrating greater speed and efficacy than complementary strand addition targeting the thrombin aptamer. Furthermore, UdgX restored the binding capacity of the anti-VEGF antibody bevacizumab that had been inhibited by a hairpin-structured aptamer. These findings highlight the versatile potential of UdgX to turn on protein functions inhibited by DNA aptamers.