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The molecular coupling between substrate recognition and ATP turnover in a AAA+ hexameric helicase loader
Neha Puri1, Amy J Fernandez1, Valerie L O'Shea Murray1,2
1Department of Biophysics and Biophysical Chemistry, Johns Hopkins School of Medicine, Baltimore, United States.
Elife
|May 26, 2021
Summary
Researchers identified a new arginine-coupler element in the DnaC ATPase, crucial for bacterial DNA replication. This discovery explains how AAA+ ATPase loaders control helicase deposition and activation, with implications for eukaryotic replication as well.
Area of Science:
- Molecular Biology
- Biochemistry
- Genetics
Background:
- DNA replication fork establishment relies on AAA+(ATPases Associated with various cellular Activities) ATPases to load ring-shaped helicases.
- The precise mechanism by which these loading factors utilize ATP to control helicase deposition remains largely unknown.
Purpose of the Study:
- To investigate the distinct roles of specific ATPase elements in *Escherichia coli* DnaC during helicase loading and DNA unwinding activation.
- To elucidate the function of a newly identified element, the arginine-coupler, in regulating DnaC's ATPase activity and responsiveness.
Main Methods:
- Biochemical dissection of *Escherichia coli* DnaC ATPase elements.
- Analysis of DnaC's role in DnaB helicase loading and activation.
- Comparative analysis of analogous elements in eukaryotic AAA+ proteins.
Main Results:
- Identified a novel arginine-coupler element in DnaC that regulates its switch-like behavior.
- Demonstrated that the arginine-coupler prevents futile ATPase cycling and maintains loader responsiveness.
- Showed that analogous elements exist in eukaryotic AAA+ proteins involved in helicase loading, polymerase clamp loading, and DNA transposases.
Conclusions:
- The ATPase cycle of AAA+ helicase loaders is channeled into productive action via specific elements like the arginine-coupler.
- The arginine-coupler is essential for controlled helicase deposition and activation, ensuring replication fidelity.
- Conserved mechanisms involving switch-like AAA+ proteins regulate DNA replication initiation across bacteria and eukaryotes.
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