World's toughest bacterium discovered

Last Updated: Mon, Sep 06, 2010 07:00 hrs

It seems scientists have discovered the world's toughest bacterium, which can survive massive exposures to gamma-radiation, ultraviolet radiation, desiccation, and other agents that kill cells by generating reactive oxygen species (ROS).

Michael J. Daly of Uniformed Services University and team previously reported that D. radiodurans accomplishes its astonishing survival feats in an unexpected way - by protecting its proteins from oxidation.

This spares DNA repair enzymes from radiation damage and allows the cells to reassemble their broken genomes with extraordinary efficiency.

The current study identifies divalent manganese-complexes in D. radiodurans cell extracts, which protect purified proteins, and Escherichia coli and human cells from extreme cellular insults caused by ionizing radiation.

When bombarded by gamma-rays, D. radiodurans appears to salvage breakdown products of protein and DNA, endowing mixtures of peptides and orthophosphate with potent ROS-scavenging activities when combined with Mn(II).

When reconstituted, the Mn-complexes were immensely protective of irradiated enzymes, preserving their structure and function, but they did not protect DNA significantly.

Prospectively, D. radiodurans has presented the scientific community with a novel and highly defensive chemical strategy to combat oxidative stress in diverse settings, including bioremediation of radioactive waste, preparation of irradiated vaccines, long-term protein storage, against ultraviolet rays during sunbathing, during radiotherapy and as we age.

The study titled 'Small-Molecule Antioxidant Proteome-Shields in Deinococcus radiodurans' appeared in PLoS ONE. (ANI)

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