Protein Conformational Dynamics Probed by Single-Molecule Electron Transfer

• Published in: Science (American Association for the Advancement of Science) Vol. 302; no. 5643; pp. 262 - 266
• Main Authors: Yang, Haw, Luo, Guobin, Karnchanaphanurach, Pallop, Louie, Tai-Man, Rech, Ivan, Cova, Sergio, Xun, Luying, Xie, X. Sunney
• Format: Journal Article
• Language: English
• Published: Washington, DC American Association for the Advancement of Science 10.10.2003; The American Association for the Advancement of Science
• Subjects: Amino Acid Substitution; Azines; Biochemistry; Biological and medical sciences; Catalysis; Catalysts; Chemical Phenomena; Chemical reactions; Chemistry, Physical; Computer Simulation; Conformational dynamics in molecular biology; Correlation; Electric properties; Electron transfer; Electrons; Enzymes; Escherichia coli - enzymology; Flavin Mononucleotide - chemistry; Flavin Mononucleotide - metabolism; Flavin-Adenine Dinucleotide - chemistry; Flavin-Adenine Dinucleotide - metabolism; Flavins; Fluorescence; FMN Reductase - chemistry; FMN Reductase - genetics; FMN Reductase - metabolism; Fundamental and applied biological sciences. Psychology; Histograms; Hydrogen Bonding; Likelihood Functions; Mathematics; Models, Molecular; Molecular biophysics; Molecular Structure; Molecules; Mutagenesis, Site-Directed; Photons; Protein Conformation; Proteins; Rapid quenching; Serine; Spectrometry, Fluorescence; Temperature; Thermodynamics; Tyrosine; United States; Electron transfer; Conformational dynamics; Protein
• ISSN: 0036-8075; 1095-9203
• DOI: 10.1126/science.1086911

Electron transfer is used as a probe for angstrom-scale structural changes in single protein molecules. In a flavin reductase, the fluorescence of flavin is quenched by a nearby tyrosine residue by means of photo-induced electron transfer. By probing the fluorescence lifetime of the single flavin on a photon-by-photon basis, we were able to observe the variation of flavin-tyrosine distance over time. We could then determine the potential of mean force between the flavin and the tyrosine, and a correlation analysis revealed conformational fluctuation at multiple time scales spanning from hundreds of microseconds to seconds. This phenomenon suggests the existence of multiple interconverting conformers related to the fluctuating catalytic reactivity.