Final Report for Grant No. DE-FG02-98ER62583 ''Functional Analysis of the Genome Sequence of Deinococcus radiodurans''

Technical Report · Wed Oct 15 04:00:00 EDT 2003

DOI:https://doi.org/10.2172/816495· OSTI ID:816495

Michael J Daly, Ph D ^[1]

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1. Uniformed Services University of the Health Sciences

Extremophiles are nearly always defined with singular characteristics that allow existence within a singular extreme environment. The bacterium Deinococcus radiodurans qualifies as a polyextremeophile, showing remarkable resistance to a range of damage caused by ionizing radiation, dessication, ultraviolet radiation, oxidizing agents, and electrophilic mutagens. D. radiodurans is most famous for its extreme resistance to ionizing radiation; it not only can grow continuously in the presence of chronic radiation (6,000 rad per hour), but it can survive acute exposures to gamma radiation that exceed 1,500,000 rads without lethality or induced mutation. These characteristics were the impetus for sequencing its genome. We completed an extensive comparative sequence analysis of the Deinococcus radiodurans (strain R1) genome. Deinococcus is the first representative with a completely sequenced genome from a bacterial branch of extremophiles - the Thermus/Deinococcus group. Phylogenetic tree analysis, combined with the identification of several synapomorphies between Thermus and Deinococcus, support that it is a very ancient branch localized in the vicinity of the bacterial tree root. Distinctive features of the Deinoccoccus genome as well as features shared with other free-living bacteria were revealed by comparison of its proteome to a collection of Clusters of Orthologous Groups of proteins (COGs). Analysis of paralogs in Deinococcus has revealed some unique protein families. In addition, specific expansions of several protein families including phosphatases, proteases, acyl transferases and MutT pyrophosphohydrolases, were detected. Genes that potentially affect DNA repair and recombination were investigated in detail. Some proteins appear to have been horizontally transferred from eukaryotes, and are not present in other bacteria. For example, three proteins homologous to plant desiccation-resistance proteins were identified and these are particularly interesting because of the positive correlation between desiccation- and radiation-resistance. Further, the D. radiodurans genome is very rich in repetitive sequences, namely IS-like transposons and small intergenic repeats. In combination, these observations suggest that several different biological mechanisms contribute to the multiple DNA repair-dependent phenotypes of this organism. The genetic mechanisms underlying the extreme radiation resistance of this organism are now being characterized experimentally using a whole genome microarray.

• Research Organization: The Henry M. Jackson Foundation (US)
• Sponsoring Organization: (US)
• DOE Contract Number: FG02-98ER62583
• OSTI ID: 816495
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
59 BASIC BIOLOGICAL SCIENCES
60 APPLIED LIFE SCIENCES
61 RADIATION PROTECTION AND DOSIMETRY
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
ACUTE EXPOSURE
ANNOTATION
COMPARATIVE GENOMICS
DEINOCOCCUS
DNA PROTECTION
DNA REPAIR
GAMMA RADIATION
GENOME
IONIZING RADIATIONS
OXIDIZERS
PHOSPHATASES
RADIATION RESISTANCE
STRUCTURAL CHEMICAL ANALYSIS
TRANSFERASES
TRANSPOSONS
ULTRAVIOLET RADIATION