Mismatch extension ability of yeast and human DNA polymerase η

M. Todd Washington, Robert E. Johnson, Satya Prakash, Louise Prakash

Research output: Contribution to journalArticlepeer-review

45 Scopus citations


DNA polymerase η (Polη) functions in error-free replication of UV-damaged DNA, and in vitro it efficiently bypasses a cis-syn T-T dimer by incorporating two adenines opposite the lesion. Steady state kinetic studies have shown that both yeast and human Polη are low-fidelity enzymes, and they misincorporate nucleotides with a frequency of 10-2-10-3 on both undamaged and T-T dimer-containing DNA templates. To better understand the role of Polη in error-free translesion DNA synthesis, here we examine the ability of Polη to extend from base mismatches. We find that both yeast and human Polη extend from mismatched base pairs with a frequency of ∼10-3 relative to matched base pairs. In the absence of efficient extension of mismatched primer termini, the ensuing dissociation of Polη from DNA may favor the excision of mismatched nucleotides by a proofreading exonuclease. Thus, we expect DNA synthesis by Polη to be more accurate than that predicted from the fidelity of nucleotide incorporation alone.

Original languageEnglish (US)
Pages (from-to)2263-2266
Number of pages4
JournalJournal of Biological Chemistry
Issue number3
StatePublished - Jan 19 2001

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology


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