The switch that does not flip: the blue-light receptor YtvA from Bacillus subtilis adopts an elongated dimer conformation independent of the activation state as revealed by a combined AUC and SAXS study.
Photoreceptors play an important role in plants and bacteria by converting extracellular stimuli into intracellular signals. One distinct class are the blue-light-sensitive phototropins harboring a light-oxygen-voltage (LOV) domain coupled to various effector domains. Photon absorption by the chromophore within the LOV domain results in an activation of the output domain via mechanisms that are hitherto not well understood. The photoreceptor YtvA from Bacillus subtilis is a bacterial analog of phototropins, consists of an LOV and a sulfate transporter/anti-sigma factor antagonist domain, and is involved in the response of the bacterium to environmental stress. We present here analytical ultracentrifugation studies and small-angle X-ray scattering experiments, showing that YtvA is a dimer. On the basis of these results, we present a low-resolution model of the dimer in the dark and the lit state of the protein. In addition, we show that YtvA does not change its oligomerization state or its overall shape upon light activation.
Jurk
Marcel
M
Leibniz-Institut für Molekulare Pharmakologie, Robert-Rössle-Str. 10, 13125 Berlin, Germany; Freie Universität Berlin, Institute of Chemistry and Biochemistry, Takustr. 3, 14195 Berlin, Germany.
Dorn
Matthias
M
Leibniz-Institut für Molekulare Pharmakologie, Robert-Rössle-Str. 10, 13125 Berlin, Germany.
Kikhney
Alexey
A
European Molecular Biology Laboratory, Notkestraße 85, Geb. 25A, 22603 Hamburg, Germany.
Svergun
Dmitri
D
European Molecular Biology Laboratory, Notkestraße 85, Geb. 25A, 22603 Hamburg, Germany.
Gärtner
Wolfgang
W
Max-Planck-Institut für Bioanorganische Chemie, Stiftstr. 34-36, 45470 Mülheim, Germany.
Schmieder
Peter
P
Leibniz-Institut für Molekulare Pharmakologie, Robert-Rössle-Str. 10, 13125 Berlin, Germany. Electronic address: schmieder@fmp-berlin.de.
D001412:Bacillus subtilis / Q000737:chemistry* / Q000378:metabolism*; D003624:Darkness; D008027:Light; D008958:Models, Molecular; D020283:Photoreceptors, Microbial / Q000737:chemistry* / Q000378:metabolism*; D055503:Protein Multimerization; D053838:Scattering, Small Angle; D014461:Ultracentrifugation
D020283:Photoreceptors, Microbial