Mechanism of error-free and semitargeted mutagenic bypass of an aromatic amine lesion by Y-family polymerase Dpo4

Olga Rechkoblit, Alexander Kolbanovskiy, Lucy Malinina, Nicholas E. Geacintov, Suse Broyde, Dinshaw J. Patel

Research output: Contribution to journalArticle

Abstract

The aromatic amine carcinogen 2-aminofluorene (AF) forms covalent adducts with DNA, predominantly with guanine at the C8 position. Such lesions are bypassed by Y-family polymerases such as Dpo4 via error-free and error-prone mechanisms. We show that Dpo4 catalyzes elongation from a correct 3′-terminal cytosine opposite [AF]G in a nonrepetitive template sequence with low efficiency. This extension leads to cognate full-length product, as well as mis-elongated products containing base mutations and deletions. Crystal structures of the Dpo4 ternary complex, with the 3′-terminal primer cytosine base opposite [AF]G in the anti conformation and with the AF moiety positioned in the major groove, reveal both accurate and misalignment-mediated mutagenic extension pathways. The mutagenic template-primer-dNTP arrangement is promoted by interactions between the polymerase and the bulky lesion rather than by a base pair-stabilized misaligment. Further extension leads to semitargeted mutations via this proposed polymerase-guided mechanism.

Original languageEnglish (US)
Pages (from-to)379-388
Number of pages10
JournalNature Structural and Molecular Biology
Volume17
Issue number3
DOIs
StatePublished - Mar 2010

ASJC Scopus subject areas

  • Structural Biology
  • Molecular Biology

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