The Class III Cyclobutane Pyrimidine Dimer Photolyase Structure Reveals a New Antenna Chromophore Binding Site and Alternative Photoreduction Pathways.
Scheerer, P., Zhang, F., Kalms, J., von Stetten, D., Krau, N., Oberpichler, I., Lamparter, T.(2015) J Biol Chem 290: 11504-11514
- PubMed: 25784552 
- DOI: https://doi.org/10.1074/jbc.M115.637868
- Primary Citation of Related Structures:  
4U63 - PubMed Abstract: 
Photolyases are proteins with an FAD chromophore that repair UV-induced pyrimidine dimers on the DNA in a light-dependent manner. The cyclobutane pyrimidine dimer class III photolyases are structurally unknown but closely related to plant cryptochromes, which serve as blue-light photoreceptors. Here we present the crystal structure of a class III photolyase termed photolyase-related protein A (PhrA) of Agrobacterium tumefaciens at 1.67-Å resolution. PhrA contains 5,10-methenyltetrahydrofolate (MTHF) as an antenna chromophore with a unique binding site and mode. Two Trp residues play pivotal roles for stabilizing MTHF by a double π-stacking sandwich. Plant cryptochrome I forms a pocket at the same site that could accommodate MTHF or a similar molecule. The PhrA structure and mutant studies showed that electrons flow during FAD photoreduction proceeds via two Trp triads. The structural studies on PhrA give a clearer picture on the evolutionary transition from photolyase to photoreceptor.
Organizational Affiliation: 
From the Charité, University Medicine Berlin, Institute of Medical Physics and Biophysics (CC2), AG Protein X-ray Crystallography and Signal Transduction, Charitéplatz 1, D-10117 Berlin, Germany, patrick.scheerer@charite.de.