HMCES Maintains Genome Integrity by Shielding Abasic Sites in Single-Strand DNA.

Mohni KN, Wessel SR, Zhao R, Wojciechowski AC, Luzwick JW, Layden H, Eichman BF, Thompson PS, Mehta KPM, Cortez D
Cell. 2019 176 (1-2): 144-153.e13

PMID: 30554877 · PMCID: PMC6329640 · DOI:10.1016/j.cell.2018.10.055

Abasic sites are one of the most common DNA lesions. All known abasic site repair mechanisms operate only when the damage is in double-stranded DNA. Here, we report the discovery of 5-hydroxymethylcytosine (5hmC) binding, ESC-specific (HMCES) as a sensor of abasic sites in single-stranded DNA. HMCES acts at replication forks, binds PCNA and single-stranded DNA, and generates a DNA-protein crosslink to shield abasic sites from error-prone processing. This unusual HMCES DNA-protein crosslink intermediate is resolved by proteasome-mediated degradation. Acting as a suicide enzyme, HMCES prevents translesion DNA synthesis and the action of endonucleases that would otherwise generate mutations and double-strand breaks. HMCES is evolutionarily conserved in all domains of life, and its biochemical properties are shared with its E. coli ortholog. Thus, HMCES is an ancient DNA lesion recognition protein that preserves genome integrity by promoting error-free repair of abasic sites in single-stranded DNA.

Copyright © 2018 Elsevier Inc. All rights reserved.

MeSH Terms (12)

5-Methylcytosine Apurinic Acid DNA DNA, Single-Stranded DNA-Binding Proteins DNA Damage DNA Repair DNA Replication Endonucleases Escherichia coli Polynucleotides Proliferating Cell Nuclear Antigen

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