DNA photolyase repairs UV-damaged DNA by photo-induced electron transfer, the rate constants of which are exponentially dependent on temperature, as shown from Marcus theory. However, how these processes occur in extremophilic organisms, inhabiting thermally extreme environments, is currently unknown. To study this problem, we have produced recombinant DNA photolyases in E.coli from two extremophiles, Sulfolobus solfataricus, a hyperthermophilic archaeon (rSsPL) and Colwellia psychrerythraea, a psychrophilic bacterium (rCpPL). Both photolyases contain a noncovalently bound FAD molecule and display unique spectral features, indicative of structural adaptations to their respective thermal environments. rSsPL repairs UV damaged DNA in-vitro with efficiency comparable to E.coli DNA photolyase, at ambient temperature. Denaturation studies on rSsPL reveal its extreme stability whereas, preliminary observations suggest that rCpPL is extremely sensitive to its thermal and aqueous environments. Further characterization of these two extremophile DNA photolyases is currently underway.

Extremophile enzymatic DNA repair

244th National Meeting (2012)

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