Human MettL3-MettL14 RNA adenine methyltransferase complex is active on double-stranded DNA containing lesions

Abstract

MettL3-MettL14 methyltransferase complex has been studied widely for its role in RNA adenine methylation. This complex is also recruited to UV- and X-ray exposed DNA damaged sites, and its methyltransfer activity is required for subsequent DNA repair, though in theory this could result from RNA methylation of short transcripts made at the site of damage. We report here that MettL3-MettL14 is active in vitro on double-stranded DNA containing a cyclopyrimidine dimer – a major lesion of UV radiation-induced products – or an abasic site or mismatches. Furthermore, N6-methyladenine (N6mA) decreases misincorporation of 8-oxo-guanine (8-oxoG) opposite to N6mA by repair DNA polymerases. When 8-oxoG is nevertheless incorporated opposite N6mA, the methylation inhibits N6mA excision from the template (correct) strand by the adenine DNA glycosylase (MYH), implying that the methylation decreases inappropriate misrepair. Finally, we observed that the N6mA reader domain of YTHDC1, which is also recruited to sites of DNA damage, binds N6mA that is located across from a single-base gap between two canonical DNA helices. This YTHDC1 complex with a gapped duplex is structurally similar to DNA complexes with FEN1 and GEN1 – two members of the nuclease family that act in nucleotide excision repair, mismatch repair and homologous recombination, and which incise distinct non-B DNA structures. Together, the parts of our study provide a plausible mechanism for N6mA writer and reader proteins acting directly on lesion-containing DNA, and suggest in vivo experiments to test the mechanisms involving methylation of adenine.

METTL3 promotes homologous recombination repair and modulates chemotherapeutic response by regulating the EGF/Rad51 axis

“…7). This result was consistent with other studies showing that YTHDC1 is recruited to sites of DNA damage, bound m 6 A RNA, and increased the activity of DSB repair (Yu et al, 2021a;Zhang et al, 2020).…”

“…Moreover, knockdown of YTHDC1 impeded METTL3-enhanced RAD51 expression and inhibited recruitment of RAD51 to damaged sites. Our data combined with the studies of Zhang et al and Yu et al demonstrate that YTHDC1 plays an important role in DNA repair (Yu et al, 2021a;Zhang et al, 2020). Our results further suggest the involvement of YTHDC1 in the regulation of EGF mRNA stability.…”

“…HR in U2OS cells exposed to X-rays or treatment with Zeocin (Zhang et al, 2020). Another recent study found that METTL3-METTL14 is active in vitro on double-stranded DNA containing a cyclopyrimidine dimer, and the m6A reader, YTHDC1, is recruited to sites of DNA damage (Yu et al, 2021a). Our data demonstrated that silencing METTL3 inhibited the repair of DSBs induced by ADR.…”

PARP dependent recruitment of RNA methylated at 8-adenosine is linked to base excision repair mechanism

“…Moreover, N6-methyladenine (N6mA) reduced misincorporation of 8-oxo-guanine (8-oxoG) opposite to N6mA by repair DNA polymerases. When 8-oxoG is incorporated into the opposite site to N6mA, this process inhibits N6mA excision from the template [48]. From this observation, it is evident that METTL3/METTL14 methyltransferases, together with m 6 A RNAs, are required for DNA damage repair mechanisms that are initiated by UV radiation [23,24].…”

“…Yu et al (2021) [48] showed that the function of the METTL3-METTL14 complex, similarly to m 6 A RNA nuclear reader YTHDC1, contributes to the repair of DNA lesions containing cyclobutene pyrimidine dimers, which are well-characterized elements that appear after UVirradiation. Moreover, N6-methyladenine (N6mA) reduced misincorporation of 8-oxo-guanine (8-oxoG) opposite to N6mA by repair DNA polymerases.…”