Cooperative interaction between AAG and UV-DDB in the removal of modified bases

Sunbok Jang, Namrata Kumar, Mathew A. Schaich, Zhou Zhong, Barbara Van Loon, Simon C. Watkins, Bennett Van Houten

Research output: Contribution to journalArticlepeer-review

6 Scopus citations


UV-DDB is a DNA damage recognition protein recently discovered to participate in the removal of 8-oxo-7,8-dihydro-2′-deoxyguanosine (8-oxoG) by stimulating multiple steps of base excision repair (BER). In this study, we examined whether UV-DDB has a wider role in BER besides oxidized bases and found it has specificity for two known DNA substrates of alkyladenine glycosylase (AAG)/N-methylpurine DNA glycosylase (MPG): 1, N6-ethenoadenine (ϵA) and hypoxanthine. Gel mobility shift assays show that UV-DDB recognizes these two lesions 4-5 times better than non-damaged DNA. Biochemical studies indicated that UV-DDB stimulated AAG activity on both substrates by 4- to 5-fold. Native gels indicated UV-DDB forms a transient complex with AAG to help facilitate release of AAG from the abasic site product. Single molecule experiments confirmed the interaction and showed that UV-DDB can act to displace AAG from abasic sites. Cells when treated with methyl methanesulfonate resulted in foci containing AAG and UV-DDB that developed over the course of several hours after treatment. While colocalization did not reach 100%, foci containing AAG and UV-DDB reached a maximum at three hours post treatment. Together these data indicate that UV-DDB plays an important role in facilitating the repair of AAG substrates.

Original languageEnglish
Pages (from-to)12856-12871
Number of pages16
JournalNucleic Acids Research
Issue number22
StatePublished - 9 Dec 2022

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© 2022 The Author(s). Published by Oxford University Press on behalf of Nucleic Acids Research.


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