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Redox properties of LOV domains: Chemical versus photochemical reduction, and influence on the photocycle

Nöll, Gilbert LU ; Hauska, Gunter; Hegemann, Peter; Lanzl, Karin; Noell, Tanja; von Sanden-Flohe, Madlene and Dick, Bernhard (2007) In ChemBioChem 8(18). p.2256-2264
Abstract
LOV (light-oxygen-voltoge-sensitive) domains comprise the lightsensitive parts of many blue light photoreceptor proteins. Photoexcitation of the chromophore flavin mononucleotide (FMN) in these LOV domains leads to formation of a covalent adduct between FMN and a cysteine residue. So for, the electronically excited singlet and triplet states of FMN have been identified as the only intermediates in the photocycles of LOV domains from several organisms. Since many flavoproteins ore redox-active, however, the photocycles of LOV domains might involve other redox states of FMN, and might be controlled by the external redox potential. Here we report on the redox properties of the LOV1 domain from phototropin of the green alga Chlamydomonas... (More)
LOV (light-oxygen-voltoge-sensitive) domains comprise the lightsensitive parts of many blue light photoreceptor proteins. Photoexcitation of the chromophore flavin mononucleotide (FMN) in these LOV domains leads to formation of a covalent adduct between FMN and a cysteine residue. So for, the electronically excited singlet and triplet states of FMN have been identified as the only intermediates in the photocycles of LOV domains from several organisms. Since many flavoproteins ore redox-active, however, the photocycles of LOV domains might involve other redox states of FMN, and might be controlled by the external redox potential. Here we report on the redox properties of the LOV1 domain from phototropin of the green alga Chlamydomonas reinhardtii. By equilibrium-redox spectropotentiometry a redox potential [E-fq/fhq (flavoquinone/flavohydroquinone)] of -290 mV vs. the normal hydrogen electrode (NHE) was determined for the wild-type domain (LOV1-wt). A similar value of -280 mV was found for the mutant LOV1-C57G, in which the photoreactive cysteine is replaced by glycine. The recovery kinetics (photoadduct--> ground state) in the photocycle of LOV1-wt are not influenced by a redox potential in the range between +500 and -260 mV versus NHE. No flavosemiquinone could be generated by chemical reduction with sodium dithionite. However photoreduction of LOV1-C57G with EDTA leads exclusively to the flavosemiquinone. This semiquinone is stable against disproportionation, and the photoreduction is not mediated by free FMN. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
redox chemistry, photoreceptors, photocycles, flavins, photochemistry
in
ChemBioChem
volume
8
issue
18
pages
2256 - 2264
publisher
John Wiley & Sons
external identifiers
  • wos:000251850900014
  • scopus:38849182429
ISSN
1439-4227
DOI
10.1002/cbic.200700304
language
English
LU publication?
yes
id
2b494143-b7ee-43c7-85e5-41529293b830 (old id 1409098)
date added to LUP
2009-06-01 16:01:21
date last changed
2017-10-29 03:29:14
@article{2b494143-b7ee-43c7-85e5-41529293b830,
  abstract     = {LOV (light-oxygen-voltoge-sensitive) domains comprise the lightsensitive parts of many blue light photoreceptor proteins. Photoexcitation of the chromophore flavin mononucleotide (FMN) in these LOV domains leads to formation of a covalent adduct between FMN and a cysteine residue. So for, the electronically excited singlet and triplet states of FMN have been identified as the only intermediates in the photocycles of LOV domains from several organisms. Since many flavoproteins ore redox-active, however, the photocycles of LOV domains might involve other redox states of FMN, and might be controlled by the external redox potential. Here we report on the redox properties of the LOV1 domain from phototropin of the green alga Chlamydomonas reinhardtii. By equilibrium-redox spectropotentiometry a redox potential [E-fq/fhq (flavoquinone/flavohydroquinone)] of -290 mV vs. the normal hydrogen electrode (NHE) was determined for the wild-type domain (LOV1-wt). A similar value of -280 mV was found for the mutant LOV1-C57G, in which the photoreactive cysteine is replaced by glycine. The recovery kinetics (photoadduct--> ground state) in the photocycle of LOV1-wt are not influenced by a redox potential in the range between +500 and -260 mV versus NHE. No flavosemiquinone could be generated by chemical reduction with sodium dithionite. However photoreduction of LOV1-C57G with EDTA leads exclusively to the flavosemiquinone. This semiquinone is stable against disproportionation, and the photoreduction is not mediated by free FMN.},
  author       = {Nöll, Gilbert and Hauska, Gunter and Hegemann, Peter and Lanzl, Karin and Noell, Tanja and von Sanden-Flohe, Madlene and Dick, Bernhard},
  issn         = {1439-4227},
  keyword      = {redox chemistry,photoreceptors,photocycles,flavins,photochemistry},
  language     = {eng},
  number       = {18},
  pages        = {2256--2264},
  publisher    = {John Wiley & Sons},
  series       = {ChemBioChem},
  title        = {Redox properties of LOV domains: Chemical versus photochemical reduction, and influence on the photocycle},
  url          = {http://dx.doi.org/10.1002/cbic.200700304},
  volume       = {8},
  year         = {2007},
}