The Department of Chemical and Systems Biology Presents

John Kuriyan, Ph.D.
Professor, Departments of Chemistry and Molecular and Cell Biology
University of California, Berkeley

Talk Title: “Deep Mutagenesis Analysis of a DNA Polymerase Clamp Loader System”

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.

Reading Material:

1. Subramanian S, Gorday K, Marcus K, Orellana MR, Ren P, Luo XR, O’Donnell ME, Kuriyan J. Allosteric communication in DNA polymerase clamp loaders relies on a critical hydrogen-bonded junction. Elife. 2021 Apr 13;10:e66181. doi: 10.7554/eLife.66181. PMID: 33847559; PMCID: PMC8121543.
2. Hidalgo F, Nocka LM, Shah NH, Gorday K, Latorraca NR, Bandaru P, Templeton S, Lee D, Karandur D, Pelton JG, Marqusee S, Wemmer D, Kuriyan J. A saturation-mutagenesis analysis of the interplay between stability and activation in Ras. Elife. 2022 Mar 11;11:e76595. doi: 10.7554/eLife.76595. PMID: 35272765; PMCID: PMC8916776.

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