DNA Polymerase I: Essential Replication Enzyme

Abstract

The role of DNA polymerase I in the replication of the Escherichia coli chromosome was summarized. The consequences in vivo of a mutation in the gene (po1A) that codes for DNA polymerase I with the effect of that mutation on the physical and catalytic properties of the mutationally altered enzyme are correlated. The nature of the enzymatic defect produced by 2 nonlethal mutations in the po1A gene, po1A1 and po1A12; and the defect resulting from the conditionally lethal mutation, po1Aexl, are discussed. Topics covered include the mechanism of polymerase action, the inadequacy of DNA polymerase I in accounting for DNA replication, the discovery of the Cairns mutant and repressed role of DNA polymerase I, nonlethal DNA polymerase I mutants, the po1A12 mutant and conditionally lethal DNA polymerase I mutants.