title: BLUF hydrogen network dynamics and UV/Vis spectra: a combined molecular dynamics and quantum chemical study.
abstract: Blue light sensing using flavin (BLUF) protein photoreceptor domains change their hydrogen bond network after photoexcitation. To explore this phenomenon, BLUF domains from R. sphaeroides were simulated using Amber99 molecular dynamics (MD). Five starting configurations were considered, to study different BLUF proteins (AppA/BlrB), Trp conformations ("W(in)"/"W(out)"), structure determination (X-ray/NMR), and finally, His protonation states. We found dependencies of the hydrogen bonds on almost all parameters. Our data show an especially strong correlation of the Trp position and hydrogen bonds involving Gln63. The latter is in some contradiction to earlier results (Obanayama et al., Photochem. Photobiol. 2008, 84 10031010). Possible origins and implications are discussed. Our calculations support conjectures that Gln63 is more flexible with Trp104 in W(in) position. Using snapshots from MD and time-dependent density functional theory, UV/vis spectra for the chromophore were determined, which account for molecular motion of the protein under ambient conditions. In accord with experiment, it is found that the UV/vis spectra of BLUF bound flavin are red-shifted and thermally broadened for all calculated π → π* transitions, relative to gas phase flavin at T = 0 K. However, differences in the spectra between the various BLUF configurations cannot be resolved with the present approach.
authors: Max-Planck-Institut für Kohlenforschung, Mülheim an der Ruhr, Germany. goetze@kofo.mpg.de
authors: Jan P
authors: JP
authors: Götze
authors: Claudio
authors: C
authors: Greco
authors: Roland
authors: R
authors: Mitrić
authors: Vlasta
authors: V
authors: Bonačić-Koutecký
authors: Peter
authors: P
authors: Saalfrank
mesh_terms: D005415:Flavins / Q000737:chemistry; D005420:Flavoproteins / Q000737:chemistry*; D006860:Hydrogen Bonding; D062105:Molecular Docking Simulation; D055668:Photochemical Processes; D011789:Quantum Theory; D012242:Rhodobacter sphaeroides / Q000737:chemistry; D013056:Spectrophotometry, Ultraviolet; D013997:Time Factors
chemical_list: D005415:Flavins; D005420:Flavoproteins