title: Direct determination of resonance energy transfer in photolyase: structural alignment for the functional state.
abstract: Photoantenna is essential to energy transduction in photoinduced biological machinery. A photoenzyme, photolyase, has a light-harvesting pigment of methenyltetrahydrofolate (MTHF) that transfers its excitation energy to the catalytic flavin cofactor FADH¯ to enhance DNA-repair efficiency. Here we report our systematic characterization and direct determination of the ultrafast dynamics of resonance energy transfer from excited MTHF to three flavin redox states in E. coli photolyase by capturing the intermediates formed through the energy transfer and thus excluding the electron-transfer quenching pathway. We observed 170 ps for excitation energy transferring to the fully reduced hydroquinone FADH¯, 20 ps to the fully oxidized FAD, and 18 ps to the neutral semiquinone FADH(•), and the corresponding orientation factors (κ(2)) were determined to be 2.84, 1.53 and 1.26, respectively, perfectly matching with our calculated theoretical values. Thus, under physiological conditions and over the course of evolution, photolyase has adopted the optimized orientation of its photopigment to efficiently convert solar energy for repair of damaged DNA.
authors.affiliation: Department of Physics, Department of Chemistry and Biochemistry, and Programs of Biophysics, Chemical Physics, and Biochemistry, The Ohio State University , 191 West Woodruff Avenue, Columbus, Ohio 43210, United States.
authors.forename: Chuang
authors.initials: C
authors.lastname: Tan
authors.forename: Lijun
authors.initials: L
authors.lastname: Guo
authors.forename: Yuejie
authors.initials: Y
authors.lastname: Ai
authors.forename: Jiang
authors.initials: J
authors.lastname: Li
authors.forename: Lijuan
authors.initials: L
authors.lastname: Wang
authors.forename: Aziz
authors.initials: A
authors.lastname: Sancar
authors.forename: Yi
authors.initials: Y
authors.lastname: Luo
authors.forename: Dongping
authors.initials: D
authors.lastname: Zhong
mesh_terms: D004255:Deoxyribodipyrimidine Photo-Lyase / Q000737:chemistry*; D004735:Energy Transfer; D004926:Escherichia coli; D029968:Escherichia coli Proteins / Q000737:chemistry*; D005182:Flavin-Adenine Dinucleotide / Q000737:chemistry; D005492:Folic Acid / Q000031:analogs & derivatives* / Q000737:chemistry; D010084:Oxidation-Reduction; D012256:Riboflavin / Q000031:analogs & derivatives / Q000737:chemistry; D013057:Spectrum Analysis
chemical_list: D029968:Escherichia coli Proteins; D005182:Flavin-Adenine Dinucleotide; C007701:factor 420; C032418:5,11-methenyltetrahydrohomofolate; D005492:Folic Acid; D004255:Deoxyribodipyrimidine Photo-Lyase; D012256:Riboflavin