Divalent Cations Increase DNA Repair Activities of Bacterial (6‐4) Photolyases |
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| Authors: | Hongju Ma Fan Zhang Elisabeth Ignatz Martin Suehnel Peng Xue Patrick Scheerer Lars Oliver Essen Norbert Krauß Tilman Lamparter |
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| Institution: | 1. Karlsruhe Institute of Technology, Botanical Institute, Karlsruhe, Germany;2. China Academy of Engineering Physics, Institute of Materials, Mianyang, China;3. Department of Chemistry, LOEWE Center for Synthetic Microbiology, Philipps University Marburg, Marburg, Germany;4. Institute of Medical Physics and Biophysics (CC2), Group Protein X‐ray Crystallography and Signal Transduction, Charité – Universit?tsmedizin Berlin, Berlin, Germany |
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| Abstract: | The (6‐4) photolyases of the FeS‐BCP group can be considered as the most ancient type among the large family of cryptochrome and photolyase flavoproteins. In contrast to other photolyases, they contain an Fe‐S cluster of unknown function, a DMRL chromophore, an interdomain loop, which could interact with DNA, and a long C‐terminal extension. We compared DNA repair and photoreduction of two members of the FeS‐BCP family, Agrobacterium fabrum PhrB and Rhodobacter sphaeroides RsCryB, with a eukaryotic (6‐4) photolyase from Ostreococcus, OsCPF, and a member of the class III CPD photolyases, PhrA from A. fabrum. We found that the low DNA repair effectivity of FeS‐BCP proteins is largely stimulated by Mg2+ and other divalent cations, whereas no effect of divalent cations was observed in OsCPF and PhrA. The (6‐4) repair activity in the presence of Mg2+ is comparable with the repair activities of the other two photolyases. The photoreduction, on the other hand, is negatively affected by Mg2+ in PhrB, but stimulated by Mg2+ in PhrA. A clear relationship of Mg2+ dependency on DNA repair with the evolutionary position conflicts with Mg2+ dependency of photoreduction. We discuss the Mg2+ effect in the context of structural data and DNA binding. |
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