Abstract
Protein interactions within the replisome (a highly coordinated protein complex) are crucial
to maintain temporal and spatial regulation for high fidelity DNA synthesis in Escherichia coli (E. coli). A
key component of these interactions is the processivity switch, ensuring smooth transition of the
replicative DNA polymerase III (Pol III) between Okazaki fragments on the lagging strand. Multiple
interaction studies between replisome components have been performed to indicate the essential roles of Pol III
(DnaE), β-clamp, DnaB helicase, DNA and the (DnaX) subunit for this switch.
Methods: Known interacting regions of both DnaE and various truncated versions of were chosen for coexpression in E. coli. Differences in the growth pattern of cells co-expressing various truncated versions of DnaX
and DnaE, on liquid and solid media were subsequently analyzed. Based on in vivo analyses to explore the
interactions between these components, an expanded model for the processivity switch is presented here.
Results: The analyses suggest that residues 481-643 of are sufficient to establish a functional interaction with
the DnaB helicase and DnaE during replication, while residues 461-480 of interact with the C-terminal tail of
DnaE to disengage Pol III from the β-clamp during processivity switching. We also propose that residues 430-
460 of are involved in sensing the DNA structure required for the processivity switch.
Conclusion: These observations expand the current understanding of processivity switching and help dissect
the regions of utilized for binding to different replisome components such as DnaB helicase, polymerase and
DNA
Atif A. Patoli, Bushra B. Patoli. (2019) In vivo investigation of interactions between replisome components in Escherichia coli: An expanded model for the processivity switch, Advancements in Life Sciences, Volume 7, Issue 2.
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