Comparison of the 5' nuclease activities of taq DNA polymerase and its isolated nuclease domain.


Many eubacterial DNA polymerases are bifunctional molecules having both polymerization (P) and 5' nuclease (N) activities, which are contained in separable domains. We previously showed that the DNA polymerase I of Thermus aquaticus (TaqNP) endonucleolytically cleaves DNA substrates, releasing unpaired 5' arms of bifurcated duplexes. Here, we compare the substrate specificities of TaqNP and the isolated 5' nuclease domain of this enzyme, TaqN. Both enzymes are significantly activated by primer oligonucleotides that are hybridized to the 3' arm of the bifurcation; optimal stimulation requires overlap of the 3' terminal nucleotide of the primer with the terminal base pair of the duplex, but the terminal nucleotide need not hybridize to the complementary strand in the substrate. In the presence of Mn2+ ions, TaqN can cleave both RNA and circular DNA at structural bifurcations. Certain anti-TaqNP mAbs block cleavage by one or both enzymes, whereas others can stimulate cleavage of nonoptimal substrates.




new topics/pols set partial results complete validated


No results available for this paper.

Entry validated by:

Log in to edit reference All References

Using Polbase tables:


Tables may be sorted by clicking on any of the column titles. A second click reverses the sort order. <Ctrl> + click on the column titles to sort by more than one column (e.g. family then name).


It is also possible to filter the table by typing into the search box above the table. This will instantly hide lines from the table that do not contain your search text.