Purification and characterization of the beta subunit of the DNA polymerase III holoenzyme of Escherichia coli.


The beta subunit of the DNA polymerase III holoenzyme has been purified 10,000-fold to homogeneity from Escherichia coli HMS-83. The native and denatured molecular weights of beta are 72,000 and 37,000, as determined by equilibrium sedimentation. Thus, beta appears to exist as a dimer when in a state free of other holoenzyme components. This conclusion is supported by the native molecular weight calculated from the sedimentation coefficient (5.0 S) and the Stokes radius (32.5 A) and subunit molecular weights determined from denaturing polyacrylamide gel electrophoresis. An antibody directed specifically against the beta subunit has been prepared and found to block the DNA polymerase III holoenzyme-catalyzed reaction, but not reactions which require only the core DNA polymerase III. Furthermore, this antibody blocks the initiation, but not the elongation reaction catalyzed by the DNA polymerase III holoenzyme. Thus, beta may only be required for formation of the initiation complex between polymerase components and a primed template. Immunoprecipitation studies demonstrate that the beta subunit forms a complex with other holoenzyme components in solution, in the absence of DNA.




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.