The molecular coupling between substrate recognition and ATP turnover in a AAA+ hexameric helicase loader

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Abstract

In many bacteria and in eukaryotes, replication fork establishment requires the controlled loading of hexameric, ring-shaped helicases around DNA by AAA+ ATPases. How loading factors use ATP to control helicase deposition is poorly understood. Here, we dissect how specific ATPase elements of E. coli DnaC, an archetypal loader for the bacterial DnaB helicase, play distinct roles in helicase loading and the activation of DNA unwinding. We identify a new element, the arginine-coupler, which regulates the switch-like behavior of DnaC to prevent futile ATPase cycling and maintains loader responsiveness to replication restart systems. Our data help explain how the ATPase cycle of a AAA+-family helicase loader is channeled into productive action on its target; comparative studies indicate elements analogous to the Arg-coupler are present in related, switch-like AAA+ proteins that control replicative helicase loading in eukaryotes, as well as polymerase clamp loading and certain classes of DNA transposases.

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All data generated during this study is included in the manuscript and supplemental files.

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Neha Puri

Department Biophysics and Biophysical Chemistry, Johns Hopkins School of Medicine, Baltimore, United States

Competing interests
Neha Puri, Neha Puri is affiliated with FogPharma. The author has no financial interests to declare..
Amy J Fernandez

Department of Biophysics and Biophysical Chemistry, Johns Hopkins School of Medicine, Baltimore, United States

Competing interests
No competing interests declared.
Valerie L O'Shea Murray

Department of Biophysics and Biophysical Chemistry, Johns Hopkins School of Medicine, Baltimore, United States

Competing interests
Valerie L O'Shea Murray, Valerie L. O'Shea Murray is affiliated with Saul Ewing Arnstein & Lehr, LLP. The author has no financial interests to declare..
Sarah McMillan

Department of Biomolecular Chemistry, University of Wisconsin School of Medicine and Public Health, Madison, United States

Competing interests
No competing interests declared.
James L Keck

Department of Biomolecular Chemistry, University of Wisconsin School of Medicine and Public Health, Madison, United States

Competing interests
No competing interests declared.
James M Berger

Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, United States

For correspondence
jberge29@jhmi.edu

Competing interests
No competing interests declared.

"This ORCID iD identifies the author of this article:" 0000-0003-0666-1240

Funding

National Institute of General Medical Sciences (R37-GM71747)

James M Berger

National Institute of General Medical Sciences (R01-GM098885)

James L Keck

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.

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This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.