TY - JOUR
T1 - Across the tree of life, radiation resistance is governed by antioxidant Mn2+, gauged by paramagnetic resonance
AU - Sharma, Ajay
AU - Gaidamakova, Elena K.
AU - Grichenko, Olga
AU - Matrosova, Vera Y.
AU - Hoeke, Veronika
AU - Klimenkova, Polina
AU - Conze, Isabel H.
AU - Volpe, Robert P.
AU - Tkavc, Rok
AU - Gostinčar, Cene
AU - Gunde-Cimerman, Nina
AU - DiRuggiero, Jocelyne
AU - Shuryak, Igor
AU - Ozarowski, Andrew
AU - Hoffman, Brian M.
AU - Daly, Michael J.
N1 - Funding Information:
ACKNOWLEDGMENTS. We thank Prof. Valeria Culotta for supplying sod− S. cerevisiae strains and Michael Woolbert (USUHS) for assistance in irradiator maintenance and calibration. This study was supported by NIH Grant GM111097 (to B.M.H.) and by funds received from Defense Threat Reduction Agency (DTRA) Grant HDTRA1620354 (to M.J.D.), DTRA Grant HDTRA1-15-1-0058 (to I.S.), and Grant FA9550-14-1-0118 (to J.D.) from the Air Force Office of Scientific Research (AFOSR). High-field EPR spectra were recorded at the NHMFL, which is funded by the National Science Foundation through Co-operative Agreement DMR-1157490 between the State of Florida and the US Department of Energy. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. The opinions expressed herein are those of the author(s), and are not necessarily representative of those of the USUHS; DTRA; AFOSR; the Department of Defense; or the US Army, Navy, or Air Force.
Publisher Copyright:
© 2017, National Academy of Sciences. All rights reserved.
PY - 2017/10/31
Y1 - 2017/10/31
N2 - Despite concerted functional genomic efforts to understand the complex phenotype of ionizing radiation (IR) resistance, a genome sequence cannot predict whether a cell is IR-resistant or not. Instead, we report that absorption-display electron paramagnetic resonance (EPR) spectroscopy of nonirradiated cells is highly diagnostic of IR survival and repair efficiency of DNA double-strand breaks (DSBs) caused by exposure to gamma radiation across archaea, bacteria, and eukaryotes, including fungi and human cells. IR-resistant cells, which are efficient at DSB repair, contain a high cellular content of manganous ions (Mn2+) in high-symmetry (H) antioxidant complexes with small metabolites (e.g., orthophosphate, peptides), which exhibit narrow EPR signals (small zero-field splitting). In contrast, Mn2+ ions in IR-sensitive cells, which are inefficient at DSB repair, exist largely as low-symmetry (L) complexes with substantially broadened spectra seen with enzymes and strongly chelating ligands. The fraction of cellular Mn2+ present as H-complexes (H-Mn2+), as measured by EPR of live, nonirradiated Mn-replete cells, is now the strongest known gauge of biological IR resistance between and within organisms representing all three domains of life: Antioxidant H-Mn2+ complexes, not antioxidant enzymes (e.g., Mn superoxide dismutase), govern IR survival. As the pool of intracellular metabolites needed to form H-Mn2+ complexes depends on the nutritional status of the cell, we conclude that IR resistance is predominantly a metabolic phenomenon. In a cross-kingdom analysis, the vast differences in taxonomic classification, genome size, and radioresistance between cell types studied here support that IR resistance is not controlled by the repertoire of DNA repair and antioxidant enzymes.
AB - Despite concerted functional genomic efforts to understand the complex phenotype of ionizing radiation (IR) resistance, a genome sequence cannot predict whether a cell is IR-resistant or not. Instead, we report that absorption-display electron paramagnetic resonance (EPR) spectroscopy of nonirradiated cells is highly diagnostic of IR survival and repair efficiency of DNA double-strand breaks (DSBs) caused by exposure to gamma radiation across archaea, bacteria, and eukaryotes, including fungi and human cells. IR-resistant cells, which are efficient at DSB repair, contain a high cellular content of manganous ions (Mn2+) in high-symmetry (H) antioxidant complexes with small metabolites (e.g., orthophosphate, peptides), which exhibit narrow EPR signals (small zero-field splitting). In contrast, Mn2+ ions in IR-sensitive cells, which are inefficient at DSB repair, exist largely as low-symmetry (L) complexes with substantially broadened spectra seen with enzymes and strongly chelating ligands. The fraction of cellular Mn2+ present as H-complexes (H-Mn2+), as measured by EPR of live, nonirradiated Mn-replete cells, is now the strongest known gauge of biological IR resistance between and within organisms representing all three domains of life: Antioxidant H-Mn2+ complexes, not antioxidant enzymes (e.g., Mn superoxide dismutase), govern IR survival. As the pool of intracellular metabolites needed to form H-Mn2+ complexes depends on the nutritional status of the cell, we conclude that IR resistance is predominantly a metabolic phenomenon. In a cross-kingdom analysis, the vast differences in taxonomic classification, genome size, and radioresistance between cell types studied here support that IR resistance is not controlled by the repertoire of DNA repair and antioxidant enzymes.
KW - DNA repair
KW - DSB
KW - Deinococcus
KW - EPR
KW - Ionizing radiation
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U2 - 10.1073/pnas.1713608114
DO - 10.1073/pnas.1713608114
M3 - Article
C2 - 29042516
AN - SCOPUS:85032740707
VL - 114
SP - E9253-E9260
JO - Proceedings of the National Academy of Sciences of the United States of America
JF - Proceedings of the National Academy of Sciences of the United States of America
SN - 0027-8424
IS - 44
ER -