A Conditional Lethal Mutant of Escherichia coli K12 Defective in the 5′ → 3′ Exonuclease Associated with DNA Polymerase I

AUTOR(ES)

Konrad, E. Bruce

RESUMO

A mutant strain of E. coli, initially identified by an abnormally high frequency of recombination, has been found to be defective in the 5′ → 3′ exonuclease associated with DNA polymerase I, but not in the polymerase activity. This defect is tolerated at 30°, but is lethal at 43°. Like other polymerase I mutants, the strain is unusually sensitive to methyl methanesulfonate and to ultraviolet irradiation; it is also unable to support the growth of phage λ defective in general recombination, and shows a reduced rate of joining of 10S “Okazaki fragments.” These results demonstrate that a functional DNA polymerase I is essential for normal growth and viability in E. coli K12.

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