Two temperature-sensitive polA mutants: an approach to the role in vivo of DNA polymerase I

DNA polymerase I (Pol I) purified from a strain carrying polA12 demonstrates a defect primarily in the polymerase portion of the molecule. The mutant enzyme is altered in its structure and template specificity. Pol I isolated from strains carrying polAexl are primarily defective in 5' in equilibrium 3' exonuclease. The polAexl lesion renders strains conditonally lethal.