Processive replication is contingent on the exonuclease subunit of DNA polymerase III holoenzyme.

Abstract:

In this report we have taken the reconstitution approach to study which subunits of the heterotrimer core polymerase (alpha, epsilon, theta) participate in the highly processive replication of long DNA templates by DNA polymerase III holoenzyme (holoenzyme). Comparison of the core and the alpha epsilon complex (the DNA polymerase and 3'-5' exonuclease subunits, respectively) shows they are both rapid and highly processive polymerases when they are reconstituted into a holoenzyme with the gamma complex (gamma delta delta' chi psi) and beta accessory proteins of holoenzyme. Specifically, holoenzyme reconstituted using either core or alpha epsilon completely replicates a uniquely primed 5.4-kilobase (kb) single-stranded DNA within 12 s in one binding event. Hence the theta subunit of core is not required for the processivity or speed of the holoenzyme. In contrast, when only the alpha subunit is reconstituted into the holoenzyme it is unable to replicate the entire 5.4-kb circle in one binding event but still retains a fairly high processivity of 1-3 kb and when given sufficient time for multiple binding events it finally finishes the entire circle. Therefore, highly processive DNA synthesis by holoenzyme is contingent on the epsilon exonuclease subunit. In light of these results the significance of the polymerase and exonuclease activities residing in two separate polypeptides is discussed.

Polymerases:

Topics:

Status:

new topics/pols set partial results complete validated

Results:

No results available for this paper.

Entry validated by:

Log in to edit reference All References

Using Polbase tables:

Sorting:

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).

Filtering:

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.