2Institute of Molecular Genetics of National Research Center “Kurchatov Institute”, 123182 Moscow, Russia
3Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, 119991 Moscow, Russia
4Institute of Biomedical Chemistry, 119121 Moscow, Russia
5Novosibirsk State University, 630090 Novosibirsk, Russia
6Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, 119991 Moscow, Russia
7Research Computing Center, Lomonosov Moscow State University, 119991 Moscow, Russia
* To whom correspondence should be addressed.
# These authors contributed equally to this study.
Received April 22, 2022; Revised May 23, 2022; Accepted May 23, 2022
Previously, we have found that a nucleic acid metabolite, 7-methylguanine (7mGua), produced in the body can have an inhibitory effect on the poly(ADP-ribose) polymerase 1 (PARP1) enzyme, an important pharmacological target in anticancer therapy. In this work, using an original method of analysis of PARP1 activity based on monitoring fluorescence anisotropy, we studied inhibitory properties of 7mGua and its metabolite, 8-hydroxy-7-methylguanine (8h7mGua). Both compounds inhibited PARP1 enzymatic activity in a dose-dependent manner, however, 8h7mGua was shown to be a stronger inhibitor. The IC50 values for 8h7mGua at different concentrations of the NAD+ substrate were found to be 4 times lower, on average, than those for 7mGua. The more efficient binding of 8h7mGua in the PARP1 active site is explained by the presence of an additional hydrogen bond with the Glu988 catalytic residue. Experimental and computational studies did not reveal the effect of 7mGua and 8h7mGua on the activity of other DNA repair enzymes, indicating selectivity of their inhibitory action.
KEY WORDS: poly(ADP-ribose) polymerase, DNA repair, inhibitor, 7-methylguanine, 8-hydroxy-7-methylguanine