5-Formylcytosine mediated DNA-peptide cross-link induces predominantly semi-targeted mutations in both Escherichia coli and human cells

Jan Henric T. Bacurio, Priscilla Yawson, Jenna Thomforde, Qi Zhang, Honnaiah Vijay Kumar, Holly Den Hartog, Natalia Y. Tretyakova, Ashis K. Basu

Research output: Contribution to journalArticlepeer-review


Histone proteins can become trapped on DNA in the presence of 5-formylcytosine (5fC) to form toxic DNA-protein conjugates. Their repair may involve proteolytic digestion resulting in DNA-peptide cross-links (DpCs). Here, we have investigated replication of a model DpC comprised of an 11-mer peptide (NH2–GGGKGLGK∗GGA) containing an oxy-lysine residue (K∗) conjugated to 5fC in DNA. Both CXG and CXT (where X = 5fC-DpC) sequence contexts were examined. Replication of both constructs gave low viability (<10%) in Escherichia coli, whereas TLS efficiency was high (72%) in HEK 293T cells. In E. coli, the DpC was bypassed largely error-free, inducing only 2 to 3% mutations, which increased to 4 to 5% with SOS. For both sequences, semi-targeted mutations were dominant, and for CXG, the predominant mutations were G→T and G→C at the 3ʹ-base to the 5fC-DpC. In HEK 293T cells, 7 to 9% mutations occurred, and the dominant mutations were the semi-targeted G → T for CXG and T → G for CXT. These mutations were reduced drastically in cells deficient in hPol η, hPol ι or hPol ζ, suggesting a role of these TLS polymerases in mutagenic TLS. Steady-state kinetics studies using hPol η confirmed that this polymerase induces G → T and T → G transversions at the base immediately 3ʹ to the DpC. This study reveals a unique replication pattern of 5fC-conjugated DpCs, which are bypassed largely error-free in both E. coli and human cells and induce mostly semi-targeted mutations at the 3ʹ position to the lesion.

Original languageEnglish (US)
Article number105786
JournalJournal of Biological Chemistry
Issue number4
StatePublished - Apr 2024

Bibliographical note

Publisher Copyright:
© 2024 The Authors


  • 5-formylcytosine
  • DNA polymerase
  • DNA replication
  • DNA-protein crosslinks
  • mutagenesis
  • peptides
  • protein-DNA interaction
  • translesion synthesis

PubMed: MeSH publication types

  • Journal Article
  • Research Support, Non-U.S. Gov't
  • Research Support, N.I.H., Extramural


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