Evidence for an imino intermediate in the DNA polymerase beta deoxyribose phosphate excision reaction.


A recent study demonstrated that rat DNA polymerase beta (beta-pol) ...
A recent study demonstrated that rat DNA polymerase beta (beta-pol) releases 5'-deoxyribose phosphate (dRP) termini from preincised apurinic/apyrimidinic DNA, a substrate generated during certain types of base excision repair. This catalytic activity resides within the amino-terminal, 8-kDa domain of beta-pol and occurs via beta-elimination as opposed to hydrolysis (Matsumoto, Y., and Kim, K. (1995) Science 269, 699-702). The latter finding suggested that the dRP excision reaction might proceed via an imine intermediate. In order to test this hypothesis, we attempted to trap beta-pol on preincised apurinic/apyrimidinic DNA using NaBH4 as the reducing agent. Both 8-kDa domain-DNA and intact beta-pol-DNA complexes were detected and identified by autoradiography coupled to immunoblotting. Our results indicate that the chemical mechanism of the beta-pol dRpase reaction does proceed through an imine enzyme-DNA intermediate and that the active site residue responsible for dRP release must therefore contain a primary amine.




new topics/pols set partial results complete validated


No results available for this paper.

Entry validated by:

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.