Structural highlights
Function[PHRA_AGRT5] Photolyase involved in the repair of UV radiation-induced DNA damage. By using blue-light energy, catalyzes the photoreactivation of cyclobutane pyrimidine dimers (CPDs), which are formed between adjacent bases on the same DNA strand upon exposure to ultraviolet radiation. Can repair CPD lesions in ssDNA as well as in dsDNA.[1] Publication Abstract from PubMedPhotolyases are proteins with an FAD chromophore that repair UV-induced pyrimidine dimers on the DNA in a light dependent manner. The cyclobutane pyrimidine dimer (CPD) 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 resolution of 1.67 Angstrom. 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 pi-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. 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, Krauss N, Oberpichler I, Lamparter T J Biol Chem. 2015 Mar 17. pii: jbc.M115.637868. PMID:25784552[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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