A. M. Pedrini, D. Geroldi, A. Siccardi
Feb 1, 1972
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Journal
European journal of biochemistry
Abstract
Nalidixic acid, a very specific inhibitor of bacterial DNA synthesis, has been studied for its action on purified enzymes acting on DNA and in subcellular DNA-synthesizing systems. The drug does not inhibit the following enzymes: DNA polymerase I, endonuclease I, exonuclease I, II and III from Escherichia coli, polynucleotide-ligase and DNA methyl-transferase from T4- infected E. coli, DNA polymerase from Bacillus subtilis. A significant inhibition of ATP-dependent DNA synthesis is observed in cells of a strain of E. coli lacking DNA polymerase I after short treatments with toluene (2 min); longer treatments reduce the rate of synthesis and abolish its sensitivity to nalidixic acid. Equally insensitive are the ATP-dependent DNA synthesizing systems bound to membrane fractions of E. coli and B. subtilis. The results suggest a mode of action through a still unidentified physiological component of the growing point apparatus, and supply a new criterion of physiological integrity of subcellular DNA-synthesizing systems, namely their sensitivity to nalidixic acid.