Biochemical characterization and mutational studies of the thermostable uracil DNA glycosylase from the hyperthermophilic euryarchaeon Thermococcus barophilus Ch5.

Biochemical characterization and mutational studies of the thermostable uracil DNA glycosylase from the hyperthermophilic euryarchaeon Thermococcus barophilus Ch5.
Int J Biol Macromol. 2019 May 14;:
Authors: Shi H, Gan Q, Jiang D, Wu Y, Yin Y, Hou H, Chen H, Xu Y, Miao L, Yang Z, Oger P, Zhang L
Abstract
Uracil DNA glycosylases (UDGs) play an important role in removing uracil from DNA to initiate DNA base excision repair. Here, we characterized biochemically a thermostable UDG from the hyperthermophilic euryarchaeon Thermococcus barophilus Ch5 (Tba UDG), and probed its mechanism by mutational analysis. The recombinant Tba UDG cleaves exclusively uracil-containing ssDNA and dsDNA at 65 °C. The enzyme displays an optimal cleavage activity at 70-75 °C. Tba UDG cleaves DNA over a wide pH spectrum ranging from 4.0 to 11.0 with an optimal pH of 7.0-9.0. In addition, Tba UDG activity is independent on a divalent metal ion; however, both Zn2+ and Cu2+ completely inhibit the enzyme activity. Tba UDG activity is also inhibited by high NaCl concentration. Tba UDG removes uracil from DNA with the following preference: U ≈ U/G > U/T ≈ U/C > U/A. Kinetic results showed that Tba UDG cleaves uracil-containing ssDNA and dsDNA at a similar rate. The mutational studies showed that the E118A, N159A and H216A mutants completely abolish cleavage activity and retain compromised binding activity while the Y127A mutant display...

Source: International Journal of Biological Macromolecules - May 13, 2019 Category: Biochemistry Authors: Shi H, Gan Q, Jiang D, Wu Y, Yin Y, Hou H, Chen H, Xu Y, Miao L, Yang Z, Oger P, Zhang L Tags: Int J Biol Macromol Source Type: research