Biochemical and Structural Characterization of Fapyâ¢dG Replication by Human DNA Polymerase ß.
bioRxiv
; 2024 Jan 16.
Article
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| MEDLINE
| ID: mdl-38293220
ABSTRACT
N6-(2-deoxy-α,ß-D-erythro-pentofuranosyl)-2,6-diamino-4-hydroxy-5-formamido-pyrimidine (Fapyâ¢dG) is formed from a common intermediate and in comparable amounts to the well-studied mutagenic DNA lesion 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-OxodGuo). Fapyâ¢dG preferentially gives rise to G â T transversions and G â A transitions. However, the molecular basis by which Fapyâ¢dG is processed by DNA polymerases during this mutagenic process remains poorly understood. To address this we investigated how DNA polymerase ß (Pol ß), a model mammalian polymerase, bypasses a templating Fapyâ¢dG, inserts Fapyâ¢dGTP, and extends from Fapyâ¢dG at the primer terminus. When Fapyâ¢dG is present in the template, Pol ß incorporates TMP less efficiently than either dCMP or dAMP. Kinetic analysis revealed that Fapyâ¢dGTP is a poor substrate but is incorporated â¼3-times more efficiently opposite dA than dC. Extension from Fapyâ¢dG at the 3'-terminus of a nascent primer is inefficient due to the primer terminus being poorly positioned for catalysis. Together these data indicate that mutagenic bypass of Fapyâ¢dG is likely to be the source of the mutagenic effects of the lesion and not Fapyâ¢dGTP. These experiments increase our understanding of the promutagenic effects of Fapyâ¢dG.
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01-internacional
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MEDLINE
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En
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BioRxiv
Año:
2024
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Article