Lesion Bypass Activity of DNA Polymerase A from the Extremely Radioresistant Organism Deinococcus radiodurans

The bacterium Deinococcus radiodurans survives extremely high exposure to ionizing radiation and extended periods of desiccation. Radiation at the survival doses is known to cause numerous DNA damage, such as hundreds of double strand breaks and single strand breaks, as well as damage of the nucleob...

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Bibliographic Details
Published in:The Journal of biological chemistry 2007-04, Vol.282 (15), p.10908-10914
Main Authors: Heinz, Kathrin, Marx, Andreas
Format: Article
Language:English
Subjects:
Cloning, Molecular
Deinococcus - enzymology
Deinococcus - genetics
Deinococcus - radiation effects
Deinococcus radiodurans
DNA Damage - genetics
DNA, Bacterial - genetics
DNA-Directed DNA Polymerase - genetics
DNA-Directed DNA Polymerase - metabolism
Escherichia coli - enzymology
Escherichia coli - genetics
Gene Expression
Gene Expression Regulation, Enzymologic
Kinetics
Nucleotides - metabolism
Radiation Tolerance - genetics
Substrate Specificity
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Summary:The bacterium Deinococcus radiodurans survives extremely high exposure to ionizing radiation and extended periods of desiccation. Radiation at the survival doses is known to cause numerous DNA damage, such as hundreds of double strand breaks and single strand breaks, as well as damage of the nucleobases. The mechanisms of D. radiodurans to survive the depicted threats are still only beginning to be understood. DNA polymerase A (PolA) has been shown to be crucially involved in irradiation resistance mechanisms of D. radiodurans. We expressed and characterized the DNA polymerase domain of PolA for the first time in vitro. The obtained enzyme is able to efficiently catalyze DNA-dependent DNA synthesis requiring Mg(II) as divalent metal ion. Additionally, strand displacement synthesis of the DNA polymerase, which is required in several repair processes, could be detected. We further found that DNA polymerase function of PolA is modulated by the presence of Mn(II). Whereas proceeding DNA synthesis of PolA was blocked by certain DNA damage that occurs through radiation of DNA, bypass was facilitated by Mn(II). Our results suggest an enzyme modulator function of Mn(II). These observations parallel reports that D. radiodurans accumulates intracellular Mn(II) in cases of irradiation and that the level of irradiation protection correlates with Mn(II) concentrations.
ISSN:0021-9258
1083-351X
DOI:10.1074/jbc.M611404200