Mechanism of error-free DNA synthesis across N1-methyl-deoxyadenosine by human DNA polymerase-l

Rinku Jain, Jayati Roy Choudhury, Angeliki Buku, Robert E. Johnson, Louise Prakash, Satya Prakash, Aneel K. Aggarwal

Research output: Contribution to journalArticle

8 Scopus citations

Abstract

N1-methyl-deoxyadenosine (1-MeA) is formed by methylation of deoxyadenosine at the N1 atom. 1-MeA presents a block to replicative DNA polymerases due to its inability to participate in Watson-Crick (W-C) base pairing. Here we determine how human DNA polymerase-l (Poll) promotes error-free replication across 1-MeA. Steady state kinetic analyses indicate that Poll is ∼100 fold more efficient in incorporating the correct nucleotide T versus the incorrect nucleotide C opposite 1-MeA. To understand the basis of this selectivity, we determined ternary structures of Poll bound to template 1-MeA and incoming dTTP or dCTP. In both structures, template 1-MeA rotates to the syn conformation but pairs differently with dTTP versus dCTP. Thus, whereas dTTP partakes in stable Hoogsteen base pairing with 1-MeA, dCTP fails to gain a "foothold" and is largely disordered. Together, our kinetic and structural studies show how Poll maintains discrimination between correct and incorrect incoming nucleotide opposite 1-MeA in preserving genome integrity.

Original languageEnglish (US)
Article number43904
JournalScientific reports
Volume7
DOIs
StatePublished - Mar 8 2017

ASJC Scopus subject areas

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