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Microbe's survival manual

Researchers uncover how D. radiodurans can withstand extreme radiation

5:11pm, September 3, 2010
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Researchers have discovered how a microbe that can withstand sizzling doses of radiation builds its protective shield. Small complexes of manganese and other substances slurp up dangerous chemicals caused by radiation, protecting Deinococcus radiodurans bacteria from radiation’s ill effects, a study appearing September 3 in PLoS ONE shows.

What’s more, these shield components can be co-opted by E. coli and human blood cells, turning these normally sensitive cells into radiation-resistant supercells, says study coauthor Michael Daly of the Uniformed Services University of the Health Sciences in Bethesda, Md.

D. radiodurans gained notoriety in 1956, when it was found flourishing in a can of irradiated ground beef. Research has shown that the superbug can easily withstand radiation doses 1,000 times higher than those required to kill a human. The hardy microbe also thrives under conditions of extreme cold, dryness, vacuum and acidity.

Oddly enough, Daly and his team found that the bug’s manganese-based shield didn’t protect DNA from radiation damage, a finding that runs contrary to an accepted model of how radiation harms cells. Instead, the manganese complexes protect proteins, including enzymes that repair and rebuild damaged DNA. “What really got us excited is that these compounds only protect proteins, not DNA,” Daly says. “The key to survival is protecting these proteins.”

Daly says the finding opens up a route to extreme radioactive resistance by supplementation alone — no genetic manipulations are required. In the future, radiation-thwarting compounds might be applied to bacteria tasked with cleaning up radioactive waste, or be used to create extremely effective vaccines by wiping out a harmful virus’s genome but leaving its proteins behind.

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