title: Structure-based approach to the photocontrol of protein folding.
abstract: Photoswitchable proteins offer exciting prospects for remote control of biochemical processes. We propose a general approach to the design of photoswitchable proteins based on the introduction of a photoswitchable intramolecular cross-linker. We chose, as a model, a FynSH3 domain for which the free energy of folding is less than the energy available from photoisomerization of the cross-linker. Taking the experimentally determined structure of the folded protein as a starting point, mutations were made to introduce pairs of Cys residues so that the distance between Cys sulfur atoms matches the ideal length of the cis form, but not the trans form, of the cross-linker. When the trans cross-linker was introduced into this L3C-L29C-T47AFynSH3 mutant, the protein was destabilized so that folded and unfolded forms coexisted. Irradiation of the cross-linker to produce the cis isomer recovered the folded, active state of the protein. This work shows that structure-based introduction of switchable cross-linkers is a feasible approach for photocontrol of folding/unfolding of globular proteins.
authors.affiliation: Department of Chemistry, University of Toronto, 80 Saint George Street, Toronto M5S 3H6 Canada.
authors.forename: Fuzhong
authors.initials: F
authors.lastname: Zhang
authors.forename: Arash
authors.initials: A
authors.lastname: Zarrine-Afsar
authors.forename: M Sameer
authors.initials: MS
authors.lastname: Al-Abdul-Wahid
authors.forename: R Scott
authors.initials: RS
authors.lastname: Prosser
authors.forename: Alan R
authors.initials: AR
authors.lastname: Davidson
authors.forename: G Andrew
authors.initials: GA
authors.lastname: Woolley
mesh_terms: D001391:Azo Compounds / Q000737:chemistry; D002151:Calorimetry; D002942:Circular Dichroism; D003432:Cross-Linking Reagents / Q000737:chemistry; D007700:Kinetics; D008958:Models, Molecular; D019906:Nuclear Magnetic Resonance, Biomolecular; D055668:Photochemical Processes; D017510:Protein Folding; D051076:Proto-Oncogene Proteins c-fyn / Q000737:chemistry*; D013056:Spectrophotometry, Ultraviolet; D013329:Structure-Activity Relationship; D018909:src Homology Domains
chemical_list: D001391:Azo Compounds; D003432:Cross-Linking Reagents; D051076:Proto-Oncogene Proteins c-fyn; C009850:azobenzene