An endogenous dAMP ligand in
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Author(s)
Maggiolo, Ailiena O.
Thomas, William C.
Meisburger, Steve P.
Boal, Amie K.
Parker, Mackenzie James
Kim, Albert Dong Woo
Ando, Nozomi
Stubbe, JoAnne
Date Issued
April 2018
Journal
Proceedings of the National Academy of Sciences
Publisher
Proceedings of the National Academy of Sciences
Citation
Parker, Mackenzie J., Ailiena O. Maggiolo, William C. Thomas, Albert Kim, Steve P. Meisburger, Nozomi Ando, Amie K. Boal, and JoAnne Stubbe. “An Endogenous dAMP Ligand inBacillus Subtilisclass Ib RNR Promotes Assembly of a Noncanonical Dimer for Regulation by dATP.” Proceedings of the National Academy of Sciences 115, no. 20 (April 30, 2018): E4594–E4603.
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Final published version
Abstract
© 2018 National Academy of Sciences. All rights reserved. The high fidelity of DNA replication and repair is attributable, in part, to the allosteric regulation of ribonucleotide reductases (RNRs) that maintains proper deoxynucleotide pool sizes and ratios in vivo. In class Ia RNRs, ATP (stimulatory) and dATP (inhibitory) regulate activity by binding to the ATP-cone domain at the N terminus of the large α subunit and altering the enzyme’s quaternary structure. Class Ib RNRs, in contrast, have a partial cone domain and have generally been found to be insensitive to dATP inhibition. An exception is the Bacillus subtilis Ib RNR, which we recently reported to be inhibited by physiological concentrations of dATP. Here, we demonstrate that the α subunit of this RNR contains tightly bound deoxyadenosine 5′-monophosphate (dAMP) in its N-terminal domain and that dATP inhibition of CDP reduction is enhanced by its presence. X-ray crystallography reveals a previously unobserved (noncanonical) α2dimer with its entire interface composed of the partial N-terminal cone domains, each binding a dAMP molecule. Using small-angle X-ray scattering (SAXS), we show that this noncanonical α2dimer is the predominant form of the dAMP-bound α in solution and further show that addition of dATP leads to the formation of larger oligomers. Based on this information, we propose a model to describe the mechanism by which the noncanonical α2inhibits the activity of the B. subtilis Ib RNR in a dATP- and dAMP-dependent manner.
MIT Department
Massachusetts Institute of Technology. Department of Biology
Massachusetts Institute of Technology. Department of Chemistry
Massachusetts Institute of Technology. Department of Physics
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DOI of Published Version
https://doi.org/10.1073/PNAS.1800356115
