An international team of researchers has used time-resolved ultrafast crystallography to follow the progress of DNA repair by a photolyase enzyme. The work is ‘the first structural characterisation of a full enzyme reaction cycle,’ says Manuel Maestre-Reyna, who led the research.
Photolyases repair DNA damage caused by ultraviolet light in bacteria, fungi, plants and some animals including marsupials. Humans and other mammals don’t contain these enzymes, but we too incur light-induced damage. One common outcome is the formation of cyclobutane pyrimidine dimers (CPDs), where two adjacent pyrimidine bases (thymine or cytosine) fuse together via a four-membered cyclobutane ring. ‘CPD formation is the main cause of skin cancer, and sunburnt skin always contains CPD lesions’, says Maestre-Reyna, a biochemist at the Institute of Biological Chemistry in Taipei, Taiwan.
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