Exogenous applications:

1
Mn-Based Radioprotectors from Deinococcus
radiodurans
Goal to characterize and harness radioprotective
Mn-complexes of D. radiodurans
Exogenous applications
(i) (ii)
in vitro
in situ
(iii)
For in vivo delivery Radioprotective liposomes
D. radiodurans
The extremely radiation resistant bacterium D.
radiodurans contains potent Mn-based antioxidants
which protect cells from radiation, desiccation
and exposure to compounds that elicit
redox-related toxicity. Daly Science 306 (2004)
Non-enzymic Mn(II) complexes mediate extreme
ionizing radiation resistance in bacteria by
protecting proteins from oxidation during
irradiation. Daly PLoS Biology 5(4) (2007)
Relevance to Air Force Antioxidant Mn-complexes
from D. radiodurans are expected to facilitate
applications which involve purified enzymes or
whole cells. For example, (i) by preventing in
vitro oxidative damage to biological fuel
cells and biosensors (ii) increasing
survival of cells engaged in in situ
bioremediation of chemical toxins and (iii)
in vivo protection from ionizing radiation by
delivery into cells using liposomes.
PI Mike Daly, USUHS (AFOSR Award Feb 2007)
From Michael J. Daly, Ph.D., Uniformed Services
University of the Health Sciences, Bethesda,
Maryland 20814-4799. Title of Project
Modulating Radiation Resistance Novel
Protection Paradigms Based on Defenses Against
Ionizing Radiation in the Extremophile
Deinococcus radiodurans. Summary In a paper
published in Science (2004), Daly reported a
chemical basis for radiation resistance in the
bacterium Deinococcus radiodurans, famous for its
extreme resistance to x-rays and gamma-rays.
Cellular accumulation of high levels of manganese
(Mn) was shown to be key to recovery from g-rays.
In a second paper to be published in PLoS Biology
(April 2007), Dalys group established a
mechanistic link between Mn(II) and protection of
proteins from radiation damage. The current
AFOSR-funded work will isolate, characterize and
purify Mn-based radioprotective complexes. Such
Mn-complexes will be examined in vitro for their
ability to protect and facilitate enzyme systems
exposed to oxidative stress (e.g., g-rays) and
in vivo for their ability to protect bacteria and
yeast from ionizing radiation, chemical toxins,
and other redox-active conditions. ? In vitro
protection Biofuel cells, enzymatic cleanup
applications. ? In situ protection
Environmental bioremediation using live cells. ?
In vivo protection Prophylaxis for exposure to
radiation or toxic chemical agents.