A radiation-resistant bacterium called Deinococcus radiodurans can withstand radiation doses thousands of times higher than what would kill a human. The secret behind this resistance is the presence of a collection of simple metabolites, which combine with manganese to form a powerful antioxidant. Now, Northwestern University’s Professor Brian Hoffman and his colleagues have discovered how this antioxidant works.
Deinococcus radiodurans. Image credit: USU / Michael Daly.
First discovered in 1956, Deinococcus radiodurans is one of the most radiation-resistant organisms known.
It was isolated in experiments aimed to determine whether canned food could be sterilized using high doses of gamma radiation.
In a new study, Professor Hoffman and co-authors 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,” Professor Hoffman said.
“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.”
In earlier studies, researchers discovered that Deinococcus radiodurans can survive 25,000 grays (or units of X- and gamma-rays).
But, in a 2022 study, Professor Hoffman and his team found that the bacterium — when dried and frozen — could weather 140,000 grays of radiation, a dose 28,000 times greater than what would kill a human.
So, if there are any slumbering, frozen microbes buried on Mars, they possibly could have survived the onslaught of galactic cosmic radiation and solar protons to this day.
Building on their efforts to understand the microbe’s radiation resistance, the researchers investigated a designer decapeptide called DP1.
When combined with phosphate and manganese, DP1 forms the free-radical-scavenging agent MDP, which successfully protects cells and proteins against radiation damage.
“This new understanding of MDP could lead to the development of even more potent manganese-based antioxidants for applications in health care, industry, defense and space exploration,” said Uniformed Services University’s Professor Michael Daly.
The results appear in the Proceedings of the National Academy of Sciences.
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Hao Yang et al. 2024. The ternary complex of Mn2+, synthetic decapeptide DP1 (DEHGTAVMLK), and orthophosphate is a superb antioxidant. PNAS 121 (51): e2417389121; doi: 10.1073/pnas.2417389121
Source : Breaking Science News