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bioRxiv · 10.1101/366252

How Mg2+ stimulates DNA repair in prokaryotic (6-4) photolyases

Lamparter, T.·Ma, H.·Käser, G.·Thoulass, K.·Krauss, N.·Gillet, N.·Elstner, M.·Holub, D.
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Abstract

Prokaryotic (6-4) photolyases branch at the base of the evolution of cryptochromes and photolyases. In the Agrobacterium (6-4) photolyase PhrB, the repair of DNA with UV-induced (6-4) pyrimidin dimers is stimulated by Mg2+. We show that Mg2+ is required for efficient lesion binding and for charge stabilization after electron transfer from the FADH- chromophore to the DNA lesion. Two highly conserved Asp residues close to the DNA binding site are essential for the Mg2+ effect. Simulations showed that two Mg2+ bind to the region around these residues. DNA repair by eukaryotic (6-4) photolyases is not increased by Mg2+. Here, the structurally overlapping region contains no Asp but positively charged Lys or Arg. During evolution, charge stabilization and DNA binding by Mg2+ was therefore replaced by a positive amino acid. We argue that this transition has evolved in a freshwater environment. Prokaryotic (6-4) photolyases usually contain an FeS cluster. DNA repair of a cyanobacterial member of this group which is missing the FeS cluster was also found to be stimulated by Mg2+.

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Lamparter, T., Ma, H., Käser, G., Thoulass, K., Krauss, N., Gillet, N., Elstner, M., Holub, D.. 2018-07-10. How Mg2+ stimulates DNA repair in prokaryotic (6-4) photolyases. https://doi.org/10.1101/366252

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