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bioRxiv · 10.1101/2023.06.14.544844

Self-reversal facilitates the resolution of HMCES-DNA protein crosslinks in cells

Rua-Fernandez, J.·Lovejoy, C. A.·Mehta, K. P. M.·Paulin, K. A.·Toudji, Y. T.·Eichman, B. F.·Cortez, D.
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Abstract

Abasic sites are common DNA lesions that stall polymerases and threaten genome stability. When located in single-stranded DNA (ssDNA), they are shielded from aberrant processing by HMCES via a DNA-protein crosslink (DPC) that prevents double-strand breaks. Nevertheless, the HMCES-DPC must be removed to complete DNA repair. Here, we found that DNA polymerase inhibition generates ssDNA abasic sites and HMCES-DPCs. These DPCs are resolved with a half-life of approximately 1.5 hours. Resolution does not require the proteasome or SPRTN protease. Instead, HMCES-DPC self-reversal is important for resolution. Biochemically, self-reversal is favored when the ssDNA is converted to duplex DNA. When the self-reversal mechanism is inactivated, HMCES-DPC removal is delayed, cell proliferation is slowed, and cells become hypersensitive to DNA damage agents that increase AP site formation. Thus, HMCES-DPC formation followed by self-reversal is an important mechanism for ssDNA AP site management.

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Rua-Fernandez, J., Lovejoy, C. A., Mehta, K. P. M., Paulin, K. A., Toudji, Y. T., Eichman, B. F., Cortez, D.. 2023-06-14. Self-reversal facilitates the resolution of HMCES-DNA protein crosslinks in cells. https://doi.org/10.1101/2023.06.14.544844

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