How ‘Conan the Bacterium’ withstands extreme radiation

Dubbed “Conan the Bacterium” for its extraordinary ability to tolerate the harshest of conditions, Deinococcus radiodurans can withstand radiation doses thousands of times higher than what would kill a human — and every other organism, for that matter.

The secret behind this impressive resistance is the presence of a collection of simple metabolites, which combine with manganese to form a powerful antioxidant. Now, chemists at Northwestern University and the Uniformed Services University (USU) have discovered how this antioxidant works.

In a new study, the researchers characterized a synthetic designer antioxidant, called MDP, which was inspired by Deinococcus radiodurans’ resilience. They found MDP’s components — manganese ions, phosphate and a small peptide — form a ternary complex that is a much more powerful protectant from radiation damage than manganese combined with either of the other individual components alone.

This discovery could eventually lead to new synthetic antioxidants specifically tailored to human needs. Applications include protecting astronauts from intense cosmic radiation during deep-space missions, preparing for radiation emergencies and producing radiation-inactivated vaccines.

“It is this ternary complex that is MDP’s superb shield against the effects of radiation,” said Northwestern’s Brian Hoffman, who conducted the study with USU’s Michael Daly. “We’ve long known that manganese ions and phosphate together make a strong antioxidant, but discovering and understanding the ‘magic’ potency provided by the addition of the third component is a breakthrough. This study has provided the key to understanding why this combination is such a powerful — and promising — radioprotectant.”

Hoffman is the Charles E. and Emma H. Morrison Professor of Chemistry and professor of molecular biosciences at Northwestern’s Weinberg College of Arts and Sciences. He also is a member of the Chemistry of Life Processes Institute and the Robert H. Lurie Comprehensive Cancer Center of Northwestern University. An expert on Deinococcus radiodurans, Daly is a professor of pathology at USU and a member of the National Academies’ Committee on Planetary Protection.

Incredible Hulk of the microbial world

The new study, published in the Proceedings of the National Academy of Sciences, builds on previous research from Hoffman’s and Daly’s collaboration, during which they sought to better understand Deinococcus radiodurans’ predicted ability to withstand radiation on Mars. In that research, Hoffman’s team at Northwestern used an advanced spectroscopy technique to measure the accumulation of manganese antioxidants in the microbes’ cells.