The insertion specificities of an oxidized dATP analogue, 
2-hydroxydeoxyadenosine 5'-triphosphate (2-OH-dATP), were determined using the 
alpha (catalytic) subunit of Escherichia coli DNA polymerase III and the 
exonuclease-deficient Klenow fragment of DNA polymerase I. In contrast to our 
previous observation that mammalian DNA polymerase alpha incorporated the 
oxidized nucleotide opposite T and C, these two E. coli DNA polymerases 
incorporated 2-OH-dATP opposite T and G on the DNA template. Steady-state 
kinetic studies indicated that the alpha subunit incorporated 2-OH-dATP 10 times 
more frequently opposite T than opposite G. On the other hand, the incorporation 
of 2-OH-dATP opposite T by the exonuclease-deficient Klenow fragment was 2 
orders of magnitude more efficient than that opposite G. These results indicate 
that the misinsertion specificity of 2-OH-dATP differs between replicative and 
repair-type DNA polymerases, and provide a biochemical basis for the mutations 
induced by 2-OH-dATP in E. coli.