title: Short-distance probes for protein backbone structure based on energy transfer between bimane and transition metal ions.
abstract: The structure and dynamics of proteins underlies the workings of virtually every biological process. Existing biophysical methods are inadequate to measure protein structure at atomic resolution, on a rapid time scale, with limited amounts of protein, and in the context of a cell or membrane. FRET can measure distances between two probes, but depends on the orientation of the probes and typically works only over long distances comparable with the size of many proteins. Also, common probes used for FRET can be large and have long, flexible attachment linkers that position dyes far from the protein backbone. Here, we improve and extend a fluorescence method called transition metal ion FRET that uses energy transfer to transition metal ions as a reporter of short-range distances in proteins with little orientation dependence. This method uses a very small cysteine-reactive dye monobromobimane, with virtually no linker, and various transition metal ions bound close to the peptide backbone as the acceptor. We show that, unlike larger fluorophores and longer linkers, this donor-acceptor pair accurately reports short-range distances and changes in backbone distances. We further extend the method by using cysteine-reactive metal chelators, which allow the technique to be used in protein regions of unknown secondary structure or when native metal ion binding sites are present. This improved method overcomes several of the key limitations of classical FRET for intramolecular distance measurements.
authors.affiliation: Department of Physiology and Biophysics, Howard Hughes Medical Institute, University of Washington, Seattle, WA 98195, USA.
authors.forename: Justin W
authors.initials: JW
authors.lastname: Taraska
authors.forename: Michael C
authors.initials: MC
authors.lastname: Puljung
authors.forename: William N
authors.initials: WN
authors.lastname: Zagotta
mesh_terms: D000465:Algorithms; D000595:Amino Acid Sequence; D001665:Binding Sites; D001643:Bridged Bicyclo Compounds / Q000737:chemistry; D019086:Bridged Bicyclo Compounds, Heterocyclic / Q000737:chemistry*; D002942:Circular Dichroism; D003545:Cysteine / Q000737:chemistry; D004735:Energy Transfer; D031541:Fluorescence Resonance Energy Transfer / Q000379:methods; D006639:Histidine / Q000737:chemistry; D008670:Metals / Q000737:chemistry*; D011485:Protein Binding; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D011506:Proteins / Q000737:chemistry*; D015203:Reproducibility of Results
chemical_list: D001643:Bridged Bicyclo Compounds; D019086:Bridged Bicyclo Compounds, Heterocyclic; D008670:Metals; D011506:Proteins; C021149:bimanes; D006639:Histidine; D003545:Cysteine; C028381:monobromobimane