High-fidelity in vivo replication of DNA base shape mimics without Watson-Crick hydrogen bonds

James C. Delaney, Paul Henderson, Sandra A. Helquist, Juan C. Morales, John M. Essigmann, Eric T. Kool

Research output: Contribution to journalArticlepeer-review

60 Scopus citations


We report studies testing the importance of Watson-Crick hydrogen bonding, base-pair geometry, and steric effects during DNA replication in living bacterial cells. Nonpolar DNA base shape mimics of thymine and adenine (abbreviated F and Q, respectively) were introduced into Escherichia coli by insertion into a phage genome followed by transfection of the vector into bacteria. Genetic assays showed that these two base mimics were bypassed with moderate to high efficiency in the cells and with very high efficiency under damage-response (SOS induction) conditions. Under both sets of conditions, the T-shape mimic (F) encoded genetic information in the bacteria as if it were thymine, directing incorporation of adenine opposite it with high fidelity. Similarly, the A mimic (Q) directed incorporation of thymine opposite itself with high fidelity. The data establish that Watson-Crick hydrogen bonding is not necessary for high-fidelity replication of a base pair in vivo. The results suggest that recognition of DNA base shape alone serves as the most powerful determinant of fidelity during transfer of genetic information in a living organism.

Original languageEnglish (US)
Pages (from-to)4469-4473
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number8
StatePublished - Apr 15 2003
Externally publishedYes


  • Difluorotoluene
  • Isostere
  • Mutagenesis
  • Replication bypass

ASJC Scopus subject areas

  • Genetics
  • General


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