Structural basis of DNA synthesis opposite 8-oxoguanine by human PrimPol primase-polymerase.
Publication Type:Journal Article
Source:Nat Commun, Volume 12, Issue 1, p.4020 (2021)
Keywords:Base Pairing, DNA Damage, DNA Primase, DNA Replication, DNA-Directed DNA Polymerase, Guanine, Humans, Mitochondria, Multifunctional Enzymes, Oxidative Stress, Protein Conformation, Reactive Oxygen Species
<p>PrimPol is a human DNA polymerase-primase that localizes to mitochondria and nucleus and bypasses the major oxidative lesion 7,8-dihydro-8-oxoguanine (oxoG) via translesion synthesis, in mostly error-free manner. We present structures of PrimPol insertion complexes with a DNA template-primer and correct dCTP or erroneous dATP opposite the lesion, as well as extension complexes with C or A as a 3'-terminal primer base. We show that during the insertion of C and extension from it, the active site is unperturbed, reflecting the readiness of PrimPol to accommodate oxoG(anti). The misinsertion of A opposite oxoG(syn) also does not alter the active site, and is likely less favorable due to lower thermodynamic stability of the oxoG(syn)•A base-pair. During the extension step, oxoG(syn) induces an opening of its base-pair with A or misalignment of the 3'-A primer terminus. Together, the structures show how PrimPol accurately synthesizes DNA opposite oxidatively damaged DNA in human cells.</p>