How Deinococcus Radiodurans thrives in extreme radiation
by Clarence Oxford
Los Angeles CA (SPX) Dec 10, 2024

Deinococcus radiodurans, nicknamed "Conan the Bacterium," is renowned for its extraordinary ability to endure extreme conditions, including radiation levels thousands of times higher than lethal doses for humans and other organisms. Researchers from Northwestern University and the Uniformed Services University (USU) have identified the mechanism behind its resilience, offering insights that could lead to significant advancements in radiation protection.

The bacterium's secret lies in a collection of simple metabolites that, when combined with manganese, create a powerful antioxidant. In a recent study, scientists analyzed a synthetic antioxidant inspired by this natural defense mechanism. Known as MDP, this antioxidant is composed of manganese ions, phosphate, and a small peptide, forming a ternary complex that surpasses the protective power of its individual components.

"This ternary complex is MDP's superb shield against the effects of radiation," explained Brian Hoffman of Northwestern University, who conducted the study with Michael Daly of USU. "We've long understood the strength of manganese ions combined with phosphate, but the addition of a peptide to form this complex provides unmatched potency."

The findings, published in the Proceedings of the National Academy of Sciences, hold promise for developing new synthetic antioxidants tailored to human needs. Potential applications include shielding astronauts from cosmic radiation during space missions, managing radiation emergencies, and creating radiation-inactivated vaccines.

Deinococcus Radiodurans: The "Incredible Hulk" of Microbes

Hoffman, the Charles E. and Emma H. Morrison Professor of Chemistry at Northwestern, collaborated with Daly, an expert in pathology and a member of the National Academies' Committee on Planetary Protection. Their work builds on previous research exploring the bacterium's predicted ability to withstand Mars-like radiation conditions.

Using advanced spectroscopy techniques, Hoffman's team measured manganese antioxidant levels in Deinococcus radiodurans cells. Their findings demonstrated a direct correlation between radiation resistance and manganese antioxidant accumulation. While earlier studies found the bacterium could survive 25,000 grays of radiation, Hoffman and Daly's 2022 study revealed that dried and frozen cells could endure an astonishing 140,000 grays, a dose 28,000 times higher than what would be fatal for humans.

This remarkable survival capacity suggests that frozen microbes on Mars, if present, might endure cosmic radiation and solar protons for extended periods.

Exploring the Power of MDP

Building on their research, the team designed and studied a synthetic decapeptide called DP1. Combined with phosphate and manganese, DP1 forms MDP, a free-radical scavenger that protects cells and proteins from radiation damage. Daly's team also demonstrated MDP's effectiveness in creating irradiated polyvalent vaccines.

Using paramagnetic resonance spectroscopy, the researchers confirmed that the ternary complex of manganese ions, phosphate, and peptide is the active component of MDP. This precise molecular assembly offers exceptional antioxidant properties.

"This understanding of MDP could drive the development of even more effective manganese-based antioxidants for applications in healthcare, industry, defense, and space exploration," Daly noted.

The ternary complex of Mn2+, synthetic decapeptide DP1 (DEHGTAVMLK), and orthophosphate represents a significant step forward in understanding how to harness nature's resilience against radiation.

Research paper

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