title: Characterization of the ground state dynamics of proteorhodopsin by NMR and optical spectroscopies.
abstract: We characterized the dynamics of proteorhodopsin (PR), solubilized in diC7PC, a detergent micelle, by liquid-state NMR spectroscopy at T = 323 K. Insights into the dynamics of PR at different time scales could be obtained and dynamic hot spots could be identified at distinct, functionally relevant regions of the protein, including the BC loop, the EF loop, the N-terminal part of helix F and the C-terminal part of helix G. We further characterize the dependence of the photocycle on different detergents (n-Dodecyl β-D-maltoside DDM; 1,2-diheptanoyl-sn-glycero-3-phosphocholine diC7PC) by ultrafast time-resolved UV/VIS spectroscopy. While the photocycle intermediates of PR in diC7PC and DDM exhibit highly similar spectral characteristics, significant changes in the population of these intermediates are observed. In-situ NMR experiments have been applied to characterize structural changes during the photocycle. Light-induced chemical shift changes detected during the photocycle in diC7PC are very small, in line with the changes in the population of intermediates in the photocycle of proteorhodopsin in diC7PC, where the late O-intermediate populated in DDM is missing and the population is shifted towards an equilibrium of intermediates states (M, N, O) without accumulation of a single populated intermediate.
authors.affiliation: Institute for Organic Chemistry and Chemical Biology, Goethe University Frankfurt, Frankfurt, Germany.
authors.forename: Jochen
authors.initials: J
authors.lastname: Stehle
authors.forename: Frank
authors.initials: F
authors.lastname: Scholz
authors.forename: Frank
authors.initials: F
authors.lastname: Löhr
authors.forename: Sina
authors.initials: S
authors.lastname: Reckel
authors.forename: Christian
authors.initials: C
authors.lastname: Roos
authors.forename: Michaela
authors.initials: M
authors.lastname: Blum
authors.forename: Markus
authors.initials: M
authors.lastname: Braun
authors.forename: Clemens
authors.initials: C
authors.lastname: Glaubitz
authors.forename: Volker
authors.initials: V
authors.lastname: Dötsch
authors.forename: Josef
authors.initials: J
authors.lastname: Wachtveitl
authors.forename: Harald
authors.initials: H
authors.lastname: Schwalbe
mesh_terms: D003902:Detergents / Q000737:chemistry; D005960:Glucosides / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008823:Micelles; D008958:Models, Molecular; D019906:Nuclear Magnetic Resonance, Biomolecular; D011487:Protein Conformation; D012243:Rhodopsin / Q000737:chemistry*; D025604:Rhodopsins, Microbial; D013057:Spectrum Analysis
chemical_list: D003902:Detergents; D005960:Glucosides; D008823:Micelles; D025604:Rhodopsins, Microbial; C413548:proteorhodopsin; C040358:dodecyl maltoside; D012243:Rhodopsin