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Structural snapshots of human DNA polymerase ? engaged on a DNA double-strand break.

ABSTRACT: Genomic integrity is threatened by cytotoxic DNA double-strand breaks (DSBs), which must be resolved efficiently to prevent sequence loss, chromosomal rearrangements/translocations, or cell death. Polymerase ? (Pol?) participates in DSB repair via the nonhomologous end-joining (NHEJ) pathway, by filling small sequence gaps in broken ends to create substrates ultimately ligatable by DNA Ligase IV. Here we present structures of human Pol? engaging a DSB substrate. Synapsis is mediated solely by Pol?, facilitated by single-nucleotide homology at the break site, wherein both ends of the discontinuous template strand are stabilized by a hydrogen bonding network. The active site in the quaternary Pol ? complex is poised for catalysis and nucleotide incoporation proceeds in crystallo. These structures demonstrate that Pol? may address complementary DSB substrates during NHEJ in a manner indistinguishable from single-strand breaks.

SUBMITTER: Kaminski AM

PROVIDER: S-EPMC7508851 | biostudies-literature | 2020 Sep

REPOSITORIES: biostudies-literature

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Structural snapshots of human DNA polymerase μ engaged on a DNA double-strand break.

Kaminski Andrea M AM Pryor John M JM Ramsden Dale A DA Kunkel Thomas A TA Pedersen Lars C LC Bebenek Katarzyna K

Nature communications 20200922 1

Genomic integrity is threatened by cytotoxic DNA double-strand breaks (DSBs), which must be resolved efficiently to prevent sequence loss, chromosomal rearrangements/translocations, or cell death. Polymerase μ (Polμ) participates in DSB repair via the nonhomologous end-joining (NHEJ) pathway, by filling small sequence gaps in broken ends to create substrates ultimately ligatable by DNA Ligase IV. Here we present structures of human Polμ engaging a DSB substrate. Synapsis is mediated solely by Po ...[more]

PMID: 32963245

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