DNA polymerase III chi subunit ties single-stranded DNA binding protein to the bacterial replication machinery.

Abstract:

Single-stranded DNA binding (SSB) protein binds to single-stranded DNA (ssDNA) at the lagging strand of the replication fork in Escherichia coli cells. This protein is essential for the survival of the E.coli cell, presumably because it shields the ssDNA and holds it in a suitable conformation for replication by DNA polymerase III. In this study we undertook a biophysical analysis of the interaction between the SSB protein of E.coli and the chi subunit of DNA polymerase III. Using analytical ultracentrifugation we show that at low salt concentrations there is an increase in the stability in the physical interaction between chi and an EcoSSB/ssDNA complex when compared to that of chi to EcoSSB alone. This increase in stability disappeared in high salt conditions. The sedimentation of an EcoSSB protein lacking its C-terminal 26 amino acids remains unchanged in the presence of chi, showing that chi interacts specifically with the C-terminus of EcoSSB. In DNA melting experiments we demonstrate that chi specifically enhances the ssDNA stabilization by EcoSSB. Thus, the binding of EcoSSB to chi at the replication fork prevents premature dissociation of EcoSSB from the lagging strand and thereby enhances the processivity of DNA polymerase III.

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.