title: Differential distortion of substrate occurs when it binds to DNA photolyase: a 2-aminopurine study.
abstract: Cyclobutylpyrimidine dimers (CPDs) are formed between adjacent pyrimidines in DNA when it is exposed to ultraviolet light. CPDs can be directly repaired by DNA photolyase (PL) upon absorption of blue-green light. We have used the fluorescent adenine analogue 2-aminopurine (2Ap) to probe the local double-helical structure of the DNA substrate when it binds to the protein. Duplex melting temperatures and van't Hoff enthalpies were obtained by both UV-vis absorption and fluorescence spectroscopies to ascertain the effect of the probe and CPD on DNA stability. Steady-state fluorescence measurements of the single- and double-stranded oligos showed that the local region around the 5'-side of the CPD lesion was more disrupted and destacked than the 3'-side in substrate-protein complexes. These results were compared with those of a protein-substrate crystal structure, demonstrating that the crystal structure and solution-state studies are in agreement with regard to the differential distortions of the target DNA at the active site of the protein.
authors.affiliation: Department of Chemistry, Temple University, 201 Beury Hall, Philadelphia, Pennsylvania 19122, USA.
authors.forename: Kongsheng
authors.initials: K
authors.lastname: Yang
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Stanley
mesh_terms: D015075:2-Aminopurine / Q000737:chemistry* / Q000378:metabolism*; D001665:Binding Sites; D004255:Deoxyribodipyrimidine Photo-Lyase / Q000737:chemistry* / Q000378:metabolism*; D008958:Models, Molecular; D015394:Molecular Structure; D011485:Protein Binding; D011487:Protein Conformation; D013379:Substrate Specificity; D013816:Thermodynamics; D044366:Transition Temperature
chemical_list: D015075:2-Aminopurine; D004255:Deoxyribodipyrimidine Photo-Lyase