Covalent DNA interstrand crosslinks (ICLs) are toxic DNA damage lesions that block the replication machinery that can cause a genomic instability. Abasic site ICLs (Ap-ICLs) are formed spontaneously when an abasic site forms a covalent bond with a base located in the opposite DNA strand.
A recently discovered pathway known to repair Ap-ICL is named after the DNA glycosylase responsible for removing Ap-ICL. NEIL3 is recruited to Ap-ICL through ubiquitylation of DNA helicase, a component of the DNA replication complex. The NEIL3 glycosylase feature multiple zinc-finger domains, binds to damaged DNA, facilitating its catalytic function. However, the precise molecular mechanism of NEIL3 glycosylase in the repair process remains elusive.
Through biochemical experiment we elucidate the detailed biochemical nature of the covalent intermediate formed between NEIL3 and Ap-ICL. This work also highlights importance of methionine removal process of NEIL3 catalytic domain to get its true catalytic activity.
We establish that the previously published catalytic mutant K82A, while not involved in catalysis, plays an essential role in DNA binding. Overall, our insights significantly contribute to our understanding of the mechanism underlying the recognition and removal of Ap-ICL by NEIL3 glycosylase during DNA replication.
*For more experimental and structural data see poster of Barbora Landová