Mechanisms of Radiation Resistance in Deinococcus radiodurans

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Mechanisms of Radiation Resistance in Deinococcus
radiodurans
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Overview

• General Characteristics of Deinococcus
• Types of Damage Deinococcus can withstand
• Mechanisms of Repair
• Relevance to Humans

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General Characteristics

• Discovered in Oregon in 1956
• Related to Deinobacter and Thermus
• Chemoorganotrophic
• Forms Pink to Red colonies
• Completely Sequenced Genome
• Resistant to the effects of radiation damage

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Colonies of D. radiodurans
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A Closer Look
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Genome of D. radiodurans
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Survival of Ionizing Radiation
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Types of Damage

• Ionizing Radiation
• UV Radiation
• Dessication
• All cause double strand breaks in DNA

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DNA at 0, 24 hr after 1.75 million rads
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Adaptations to Survive Radiation

• Multigenomic
• uvrA encodes for endonuclease a
• uvsC,D,E encodes for endonuclease b
• DNA polymerase
• Rec A responsible for homologous recombination
• Pigmented carentenoids and enzymes
• DNA replication halted during repair
• LifeSaver Theory

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Controversy of Evolution

• Evolved from 2 billion years ago when Earth was
  bombarded with radiation
• Adapted to dehydration, coincidentally resistant
  to radiation damage
• Contaminant from space?

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Relevance to Humans

• Bioremediation of weapons waste
• Insight into eukaryotic UV recovery mechanisms

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Genetics Organization
Chromosome 2412,348 bp
Megaplasmid MP1117,466 bp
Plasmid CP145,704 bp
Chromosome 1 2,648,638 bp