@article{b76d02587f38401cae448779c28d2a2e,
title = "Structures of Class Id Ribonucleotide Reductase Catalytic Subunits Reveal a Minimal Architecture for Deoxynucleotide Biosynthesis",
abstract = " Class I ribonucleotide reductases (RNRs) share a common mechanism of nucleotide reduction in a catalytic α subunit. All RNRs initiate catalysis with a thiyl radical, generated in class I enzymes by a metallocofactor in a separate β subunit. Class Id RNRs use a simple mechanism of cofactor activation involving oxidation of a Mn II 2 cluster by free superoxide to yield a metal-based Mn III Mn IV oxidant. This simple cofactor assembly pathway suggests that class Id RNRs may be representative of the evolutionary precursors to more complex class Ia-c enzymes. X-ray crystal structures of two class Id α proteins from Flavobacterium johnsoniae (Fj) and Actinobacillus ureae (Au) reveal that this subunit is distinctly small. The enzyme completely lacks common N-terminal ATP-cone allosteric motifs that regulate overall activity, a process that normally occurs by dATP-induced formation of inhibitory quaternary structures to prevent productive β subunit association. Class Id RNR activity is insensitive to dATP in the Fj and Au enzymes evaluated here, as expected. However, the class Id α protein from Fj adopts higher-order structures, detected crystallographically and in solution. The Au enzyme does not exhibit these quaternary forms. Our study reveals structural similarity between bacterial class Id and eukaryotic class Ia α subunits in conservation of an internal auxiliary domain. Our findings with the Fj enzyme illustrate that nucleotide-independent higher-order quaternary structures can form in simple RNRs with truncated or missing allosteric motifs.",
author = "Rose, {Hannah R.} and Maggiolo, {Ailiena O.} and McBride, {Molly J.} and Palowitch, {Gavin M.} and Pandelia, {Maria Eirini} and Davis, {Katherine M.} and Yennawar, {Neela H.} and Boal, {Amie K.}",
note = "Funding Information: Portions of this work were conducted at the Advanced Photon Source (APS), a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract DE-AC02- 06CH11357. GM/CA at APS has been funded in whole or in part with Federal funds from the National Cancer Institute (ACB-12002) and the National Institute of General Medical Sciences (NIGMS) (AGM-12006). The Eiger 16M detector was funded by the National Institutes of Health (NIH) Office of Research Infrastructure Programs, High-End Instrumentation Grant (1S10OD012289-01A1). Use of LS-CAT Sector 21 was supported by the Michigan Economic Development Corp. and the Michigan Technology Tri-Corridor Grant (085P1000817). Portions of this work are based upon research conducted at the Cornell High Energy Synchrotron Source (CHESS), which is supported by the National Science Foundation (NSF) and the NIH/NIGMS under NSF Grant DMR-1332208, using the Macromolecular Diffraction at CHESS (MacCHESS) facility, which is supported by Grant GM-103485 from the NIH/NIGMS. The authors thank Richard Gillilan and Jesse Hopkins for help with small-angle X-ray scattering experiments, Manas Ghosh for technical assistance and reagents, and Jens Kaiser (Beckman Institute Molecular Observatory, California Institute of Technology, Pasadena, CA) for helpful discussion and critical analysis of the Fj crystal structure. Funding Information: *E-mail: akb20@psu.edu. ORCID Hannah R. Rose: 0000-0002-7982-2001 Katherine M. Davis: 0000-0002-0258-8907 Amie K. Boal: 0000-0002-1234-8472 Present Address ⊥A.O.M.: Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91106. Funding This work was supported by grants from the Searle Scholars Program (to A.K.B.) and the National Institutes of Health (GM119707 to A.K.B.). K.M.D. is grateful for the support from the Arnold O. Beckman Postdoctoral Fellowship Program. Notes The authors declare no competing financial interest. Publisher Copyright: Copyright {\textcopyright} 2019 American Chemical Society.",
year = "2019",
month = apr,
day = "9",
doi = "10.1021/acs.biochem.8b01252",
language = "English (US)",
volume = "58",
pages = "1845--1860",
journal = "Biochemistry",
issn = "0006-2960",
publisher = "American Chemical Society",
number = "14",
}