Allosteric communication in DNA polymerase clamp loaders relies on a critical hydrogen-bonded junction
- University of California, Berkeley, United States
- Howard Hughes Medical Institute, Rockefeller University, United States
Abstract
Clamp loaders are AAA+ ATPases that load sliding clamps onto DNA. We mapped the mutational sensitivity of the T4 bacteriophage sliding clamp and clamp loader by deep mutagenesis, and found that residues not involved in catalysis or binding display remarkable tolerance to mutation. An exception is a glutamine residue in the AAA+ module (Gln 118) that is not located at a catalytic or interfacial site. Gln 118 forms a hydrogen-bonded junction in a helical unit that we term the central coupler, because it connects the catalytic centers to DNA and the sliding clamp. A suppressor mutation indicates that hydrogen bonding in the junction is important, and molecular dynamics simulations reveal that it maintains rigidity in the central coupler. The glutamine-mediated junction is preserved in diverse AAA+ ATPases, suggesting that a connected network of hydrogen bonds that links ATP molecules is an essential aspect of allosteric communication in these proteins.
Data availability
All data generated or analyzed during this study are included in the manuscript and supporting files. Source data files with raw counts and relative fitness scores are included.
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Author details
Funding
Howard Hughes Medical Institute
- Subu Subramanian
- Kent Gorday
- Peter Ren
- Xiao Ran Luo
- John Kuriyan
Amgen Foundation
- Matthew R Orellana
National Institutes of Health (5T32AI100829-07)
- Kent Gorday
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Copyright
© 2021, Subramanian et al.
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.
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Allosteric communication in DNA polymerase clamp loaders relies on a critical hydrogen-bonded junction
eLife 10:e66181.
https://doi.org/10.7554/eLife.66181
