Kopka, Benita and Magerl, Kathrin and Savitsky, Anton and Davari, Mehdi D. and Roellen, Katrin and Bocola, Marco and Dick, Bernhard and Schwaneberg, Ulrich and Jaeger, Karl-Erich and Krauss, Ulrich (2017) Electron transfer pathways in a light, oxygen, voltage (LOV) protein devoid of the photoactive cysteine. SCIENTIFIC REPORTS, 7: 13346. ISSN 2045-2322,
Full text not available from this repository. (Request a copy)Abstract
Blue-light absorption by the flavin chromophore in light, oxygen, voltage (LOV) photoreceptors triggers photochemical reactions that lead to the formation of a flavin-cysteine adduct. While it has long been assumed that adduct formation is essential for signaling, it was recently shown that LOV photoreceptor variants devoid of the photoactive cysteine can elicit a functional response and that flavin photoreduction to the neutral semiquinone radical is sufficient for signal transduction. Currently, the mechanistic basis of the underlying electron-(eT) and proton-transfer (pT) reactions is not well understood. We here reengineered pT into the naturally not photoreducible iLOV protein, a fluorescent reporter protein derived from the Arabidopsis thaliana phototropin-2 LOV2 domain. A single aminoacid substitution (Q489D) enabled efficient photoreduction, suggesting that an eT pathway is naturally present in the protein. By using a combination of site-directed mutagenesis, steady-state UV/ Vis, transient absorption and electron paramagnetic resonance spectroscopy, we investigate the underlying eT and pT reactions. Our study provides strong evidence that several Tyr and Trp residues, highly conserved in all LOV proteins, constitute the eT pathway for flavin photoreduction, suggesting that the propensity for photoreduction is evolutionary imprinted in all LOV domains, while efficient pT is needed to stabilize the neutral semiquinone radical.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | ESCHERICHIA-COLI THIOREDOXIN; INTRAPROTEIN ELECTRON; DNA PHOTOLYASE; CHLAMYDOMONAS PHOTOTROPIN; RIBONUCLEOTIDE REDUCTASE; FLAVIN MONONUCLEOTIDE; RECEPTOR PHOTOTROPIN; VERSATILE PEROXIDASE; PLANT CRYPTOCHROME; PULSE-RADIOLYSIS; |
| Subjects: | 500 Science > 540 Chemistry & allied sciences |
| Divisions: | Chemistry and Pharmacy > Institut für Physikalische und Theoretische Chemie > Chair of Chemistry III - Physical Chemistry (Molecular Spectroscopy and Photochemistry) > Prof. Dr. Bernhard Dick |
| Depositing User: | Dr. Gernot Deinzer |
| Date Deposited: | 14 Dec 2018 13:19 |
| Last Modified: | 25 Feb 2019 15:12 |
| URI: | https://pred.uni-regensburg.de/id/eprint/1996 |
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