Mammalian DNA polymerase β can substitute for DNA polymerase I during DNA replication in Escherichia coli

Joann B. Sweasy, Lawrence A. Loeb

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Mammalian DNA polymerase β is the smallest known eukaryotic polymerase and is expressed as an active protein in Escherichia coli harboring a plasmid containing its cDNA. Since some catalytic functions of DNA polymerase β and E. coli DNA polymerase I are similar, we wished to determine if DNA polymerase β could substitute for DNA polymerase I in bacteria. We found that the expression of mammalian DNA polymerase β in E. coli restored growth in a DNA polymerase I-defective bacterial mutant. Sucrose density gradient analysis revealed that DNA polymerase β complements the replication defect in the mutant by increasing the rate of joining of Okazaki fragments. These findings demonstrate that DNA polymerase β, believed to function in DNA repair in mammalian cells, can also function in DNA replication. Moreover, this complementation system will permit study of the in vivo function of altered species of DNA polymerase β, an analysis currently precluded by the difficulty in isolating mutants in mammalian cells.

Original languageEnglish (US)
Pages (from-to)1407-1410
Number of pages4
JournalJournal of Biological Chemistry
Issue number3
StatePublished - Jan 25 1992
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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