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First evidence for phototropin-related blue-light receptors in prokaryotes

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http://pubman.mpdl.mpg.de/cone/persons/resource/persons78532

Quest,  B.
Oesterhelt, Dieter / Membrane Biochemistry, Max Planck Institute of Biochemistry, Max Planck Society;

http://pubman.mpdl.mpg.de/cone/persons/resource/persons77993

Gärtner,  W.
Oesterhelt, Dieter / Membrane Biochemistry, Max Planck Institute of Biochemistry, Max Planck Society;

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Citation

Losi, A., Polverini, E., Quest, B., & Gärtner, W. (2002). First evidence for phototropin-related blue-light receptors in prokaryotes. Biophysical Journal, 82(5), 2627-2634.


Cite as: http://hdl.handle.net/11858/00-001M-0000-0010-6F4A-2
Abstract
A prokaryotic protein, YtvA from Bacillus subtilis, was found to possess a light, oxygen, voltage (LOV) domain sharing high homology with the photoactive, flavin mononucleotide (FMN)- binding LOV domains of phototropins (phot), blue-light photoreceptors for phototropism in higher plants. Computer- based three-dimensional modeling suggests that YtvA-LOV binds FMN in a similar pocket as phot-LOVs. Recombinant YtvA indeed exhibits the same spectroscopical features and blue-light- induced photochemistry as phot-LOVs, with the reversible formation of a blue-shifted photoproduct, assigned to an FMN- cysteine thiol adduct (Thio(383)). By means of laser-flash photolysis and time-resolved optoacoustic experiments, we measured the quantum yield of formation for Thio(383), Phi(Thio) = 0.49, and the enthalpy change, DeltaH(Thio) = 135 kJ/mol, with respect to the parent state. The formation of Thio(383) is accompanied by a considerable volume contraction, DeltaV(Thio) = -13.5 ml/mol. Similar to phot-LOVs, Thio(383) is formed from the decay of a red-shifted transient species, T- 650, within 2 mus. In both YtvA and free FMN, this transient has an enthalpy content of similar to200 kJ/mol, and its formation is accompanied by a small contraction, DeltaV(T) approximate to -1.5 ml/mol, supporting the assignment of T-650 to the FMN triplet state, as suggested by spectroscopical evidences. These are the first studies indicating that phototropin-related, blue-light receptors may exist also in prokaryotes, besides constituting a steadily growing family in plants.