PrimPol-dependent single-stranded gap formation mediates homologous recombination at bulky DNA adducts

Abstract

Stalled replication forks can be restarted and repaired by RAD51-mediated homologous recombination (HR), but HR can also perform post-replicative repair after bypass of the obstacle. Bulky DNA adducts are important replication-blocking lesions, but it is unknown whether they activate HR at stalled forks or behind ongoing forks. Using mainly BPDE-DNA adducts as model lesions, we show that HR induced by bulky adducts in mammalian cells predominantly occurs at post-replicative gaps formed by the DNA/RNA primase PrimPol. RAD51 recruitment under these conditions does not result from fork stalling, but rather occurs at gaps formed by PrimPol re-priming and resection by MRE11 and EXO1. In contrast, RAD51 loading at double-strand breaks does not require PrimPol. At bulky adducts, PrimPol promotes sister chromatid exchange and genetic recombination. Our data support that HR at bulky adducts in mammalian cells involves post-replicative gap repair and define a role for PrimPol in HR-mediated DNA damage tolerance.

Metadata

Authors/Creators:

Piberger, A.L.
Bowry, A.
Kelly, R.D.W.
Walker, A.K.
González-Acosta, D.
Bailey, L.J.
Doherty, A.J.
Méndez, J.
Morris, J.R.
Bryant, H.E. https://orcid.org/0000-0003-2720-7020
Petermann, E.

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Keywords:

Cancer; Genomic instability; Mutation

Dates: