Covalent DNA-protein cross-links are toxic DNA lesions that interfere with essential biological processes,which can cause serious biological consequences,such as genomic instability and protein misexpression.5-Formyluracil (5fU) as an important modification in DNA,which is mainly from oxidative damage,exists in a variety of cells and tissues.We have reported that 5flJ mediated DNA-protein conjugates could exist in human cells[Zhou et al.CCS Chem.2 (2020) 54-63].We now aimed to explore its potential biological effects in vitro and in vivo.In this paper,we firstly reported that 5fU intermediated DNA-peptide or DNA-protein conjugates (both were called DPCs) could inhibit different polymerases bypass or cause mutations.Then we further investigated the functional impacts caused by 5fU-mediated DPCs,which appeared in different gene expression components[in the promoter sequence or 5\'-untranslated regions(UTR)].These results together may contribute to a broader understanding of DNA-protein interactions as well as the biological functions associated with 5fU.