Sep. 28, 2007 Researchers have completed the whole-genome sequence of Deinococcus geothermalis, which is only the second extremely radiation- and desiccation-resistant bacterium to be sequenced.
The first was for the Guinness World Records-holder Deinococcus radiodurans, which for 50 years has been the subject of extensive investigations aimed at solving the mystery of how this microbe and its close relatives survive immense doses of x-rays and gamma-rays.
Most surprisingly, many of the unique D. radiodurans genes that were strongly implicated in resistance over the last decade have turned out to be unrelated to its survival, and are not present in D. geothermalis.
Using computer-based systems to compare the D. geothermalis genome sequence with the sequence of D. radiodurans, a minimal set of genes which encode extreme resistance was defined. Far fewer genes than initially believed appear to be responsible for the extreme resistance trait, which bodes well for the long-term prospects of conferring radiation resistance to other organisms.
The phenomenal resistance of Deinococcus bacteria has given rise to numerous descriptions of their origin, including that they evolved on Mars under harsh cosmic radiation. The present analysis firmly places the origin of Deinococcus bacteria on Earth, where the evolutionary steps that led to their survival mechanisms clearly occurred in their terrestrial ancestors - most likely in a desert near you.
Results of a recent study titled "Deinococcus geothermalis: The Pool of Extreme Radiation Resistance Genes Shrinks," will be published in the Sept. 26 edition of PLoS One.
The study was headed by Michael J. Daly, Ph.D., associate professor at the Uniformed Services University of the Health Sciences' (USU), Department of Pathology.
Deinococcus geothermalis was chosen for whole-genome sequencing by the U. S. Department of Energy (DOE), Office of Science, Office of Biological and Environmental Research with Dr. Daly as the Principal Investigator. The genome sequence was acquired at the DOE-Joint Genome Institute (JGI), Walnut Creek, CA, and subjected to comparative analysis at the National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health (NIH), Bethesda, Md. D. geothermalis was previously engineered by Daly's group for cleanup of radioactive waste sites. The three-year project was a collaboration between USU, DOE-JGI, NIH, DOE's Advanced Photon Source and Pacific Northwest National Laboratory, and the Russian Academy of Sciences.
Citation: Makarova KS, Omelchenko MV, Gaidamakova EK, Matrosova VY, Vasilenko A, et al (2007) Deinococcus geothermalis: The Pool of Extreme Radiation Resistance Genes Shrinks. PLoS ONE 2(9): e955. doi:10.1371/journal.pone.0000955
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