7-Methylguanine Explained

7-Methylguanine is a modified purine nucleobase. It is a methylated version of guanine. The 7-methylguanine nucleoside is called 7-methylguanosine. However, the free 7-methylguanine base is not involved in the synthesis of nucleotides and not incorporated directly into nucleic acids.^{[1] [2]} 7-Methylguanine is a natural inhibitor of poly (ADP-ribose) polymerase (PARP) and tRNA guanine transglycosylase (TGT) - and thus may exert anticancer activity.^{[3] [4] [5]} For example, it was demonstrated that 7-methylguanine could accelerate apoptotic death of BRCA1-deficient breast cancer cells induced by cisplatin and doxorubicin.^[6]

Notes and References

1. 5669851 . 1968 . Craddock . VM . Mattocks . AR . Magee . PN . The fate of 7[14C]-methylguanine after administration to the rat . 109 . 75–78 . Biochem. J. . 1 . 10.1042/bj1090075. 1186754 .
2. 6835224 . 1983 . Kaina . B . Heindorff . K . Aurich . O . O6-methylguanine, but not N7-methylguanine or N3-methyladenine, induces gene mutations, sister-chromatid exchanges and chromosomal aberrations in Chinese hamster cells . 108 . 279–292 . Mutat. Res. . 1–3 . 10.1016/0027-5107(83)90126-4.
3. 32245127 . 2020 . Nilov . D . Maluchenko . N . Kurgina . T . Pushkarev . S . Lys . A . Kutuzov . M . Gerasimova . N . Feofanov . A . Švedas . V . Lavrik . O . Studitsky . VM . Inhibition of poly(ADP-ribose) polymerase by nucleic acid metabolite 7-methylguanine . 21 . 2159 . Int. J. Mol. Sci. . 6 . 10.3390/ijms21062159. 7139824 . free .
4. 33801950 . 2021 . Manasaryan . G . Suplatov . D . Pushkarev . S . Drobot . V . Kuimov . A . Švedas . V . Nilov . D . Bioinformatic analysis of the nicotinamide binding site in poly(ADP-ribose) polymerase family proteins . 13 . 1201 . Cancers . 6 . 10.3390/cancers13061201. 8002165 . free .
5. 6696916 . 1984 . Farkas . WR . Jacobson . KB . Katze . JR . Substrate and inhibitor specificity of tRNA-guanine ribosyltransferase . 781 . 64–75 . Biochim. Biophys. Acta . 1–2 . 10.1016/0167-4781(84)90124-6.
6. 27437145 . 2016 . Nilov . DK . Tararov . VI . Kulikov . AV . Zakharenko . AL . Gushchina . IV . Mikhailov . SN . Lavrik . OI . Švedas . VK . Inhibition of poly(ADP-ribose) polymerase by nucleic acid metabolite 7-methylguanine . 8 . 108–115 . Acta Naturae. 2 . 10.32607/20758251-2016-8-2-108-115 . 4947994 .