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Title: 5-Formylcytosine mediated DNA-protein cross-links block DNA replication and induce mutations in human cells.

Authors: Ji, Shaofei; Fu, Iwen; Naldiga, Spandana; Shao, Hongzhao; Basu, Ashis K; Broyde, Suse; Tretyakova, Natalia Y

Published In Nucleic Acids Res, (2018 07 27)

Abstract: 5-Formylcytosine (5fC) is an epigenetic DNA modification introduced via TET protein-mediated oxidation of 5-methyl-dC. We recently reported that 5fC form reversible DNA-protein conjugates (DPCs) with histone proteins in living cells (Ji et al. (2017) Angew. Chem. Int. Ed., 56:14130-14134). We now examined the effects of 5fC mediated DPCs on DNA replication. Synthetic DNA duplexes containing site-specific DPCs between 5fC and lysine-containing proteins and peptides were subjected to primer extension experiments in the presence of human translesion synthesis DNA polymerases η and κ. We found that DPCs containing histones H2A or H4 completely inhibited DNA replication, but the replication block was removed when the proteins were subjected to proteolytic digestion. Cross-links to 11-mer or 31-mer peptides were bypassed by both polymerases in an error-prone manner, inducing targeted C→T transitions and -1 deletions. Similar types of mutations were observed when plasmids containing 5fC-peptide cross-links were replicated in human embryonic kidney (HEK) 293T cells. Molecular simulations of the 11-mer peptide-dC cross-links bound to human polymerases η and κ revealed that the peptide fits well on the DNA major groove side, and the modified dC forms a stable mismatch with incoming dATP via wobble base pairing in the polymerase active site.

PubMed ID: 29905846 Exiting the NIEHS site

MeSH Terms: Cytosine/analogs & derivatives*; Cytosine/chemistry; DNA Replication*; DNA-Directed DNA Polymerase/metabolism; DNA/chemistry*; HEK293 Cells; Histones; Humans; Molecular Dynamics Simulation; Mutation*; Peptides

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