Zirak, P. and Penzkofer, Alfons and Hegemann, P. and Mathes, T. (2007) Photo dynamics of BLUF domain mutant H44R of AppA from Rhodobacter sphaeroides. CHEMICAL PHYSICS, 335 (1). pp. 15-27. ISSN 0301-0104, 1873-4421
Full text not available from this repository. (Request a copy)Abstract
The photo-cycle dynamics of the H44R mutant of the BLUF domain of the transcriptional anti-repressor protein AppA (AppA-H44R) from the non-sulfur anoxyphototropic purple bacterium Rhodobacter sphaeroides is studied in order to gain information on the involvement of His44 in the photo-cyclic mechanism of the AppA BLUF domain and to add information to the involved processes. The amino acid residue histidine at position 44 is replaced by arginine. A 12 nm red-shifted signalling state is formed upon blue-light excitation, while in wild-type AppA (AppA-wt) the red-shift is 16 nm. The recovery to the receptor dark state is approximately a factor of 2.5 faster (T-rec approximate to 6.5 min) than the recovery of the wild-type counterpart. Extended light exposure of the mutant causes photo-degradation of flavin (mainly free flavin conversion to lumichrome and re-equilibration between free and non-covalently bound flavin) and protein aggregation (showing up as light scattering). No photo-degradation was observed for AppA-wt. The quantum efficiency of signalling-state formation determined by intensity dependent absorption measurements is found to be phi(s) approximate to 0.3 (for AppA-wt: phi(s) approximate to 0.24). A two-component single-exponential fluorescence relaxation was observed, which is interpreted as fast fluorescence quenching to an equilibrium value by photo-induced electron transfer followed by slower fluorescence decay due to charge recombination. Based on the experimental findings, an extended photo-cycle model for BLUF domains is proposed. (c) 2007 Elsevier B.V. All rights reserved.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | FLAVIN ADENINE-DINUCLEOTIDE; INDUCED STRUCTURAL-CHANGES; SYNECHOCYSTIS SP PCC6803; EMISSION SPECTROSCOPIC CHARACTERIZATION; MEDIATED SIGNAL-TRANSDUCTION; FAD-BINDING DOMAIN; AQUEOUS-SOLUTION; CHLAMYDOMONAS-REINHARDTII; LIGHT PHOTORECEPTORS; TRANSCRIPTIONAL ANTIREPRESSOR; BLUE domain mutant; AppA; Rhodobacter sphaeroides; blue-light photoreceptor; flavoprotein; flavins; FAD; FMN; riboflavin; photodegradation; absorption spectroscopy; fluorescence spectroscopy; photo-cycle; photo-induced reduced electron transfer; charge recombination; signalling-state formation |
| Subjects: | 500 Science > 530 Physics |
| Divisions: | Physics > Institute of Experimental and Applied Physics > Alumni or Retired Professors > Group Alfons Penzkofer |
| Depositing User: | Dr. Gernot Deinzer |
| Date Deposited: | 09 Dec 2020 14:56 |
| Last Modified: | 09 Dec 2020 14:56 |
| URI: | https://pred.uni-regensburg.de/id/eprint/32758 |
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