title: Aureochrome 1 illuminated: structural changes of a transcription factor probed by molecular spectroscopy.
abstract: Aureochrome 1 from Vaucheria frigida is a recently identified blue-light receptor that acts as a transcription factor. The protein comprises a photosensitive light-, oxygen- and voltage-sensitive (LOV) domain and a basic zipper (bZIP) domain that binds DNA rendering aureochrome 1 a prospective optogenetic tool. Here, we studied the photoreaction of full-length aureochrome 1 by molecular spectroscopy. The kinetics of the decay of the red-shifted triplet state and the blue-shifted signaling state were determined by time-resolved UV/Vis spectroscopy. It is shown that the presence of the bZIP domain further prolongs the lifetime of the LOV390 signaling state in comparison to the isolated LOV domain whereas bound DNA does not influence the photocycle kinetics. The light-dark Fourier transform infrared (FTIR) difference spectrum shows the characteristic features of the flavin mononucleotide chromophore except that the S-H stretching vibration of cysteine 254, which is involved in the formation of the thio-adduct state, is significantly shifted to lower frequencies compared to other LOV domains. The presence of the target DNA influences the light-induced FTIR difference spectrum of aureochrome 1. Vibrational bands that can be assigned to arginine and lysine side chains as well to the phosphate backbone, indicate crucial changes in interactions between transcription factor and DNA.
authors: Experimental Molecular Biophysics, Freie Universität Berlin, Berlin, Germany.
authors: Silke
authors: S
authors: Kerruth
authors: Experimental Molecular Biophysics, Freie Universität Berlin, Berlin, Germany.
authors: Kenichi
authors: K
authors: Ataka
authors: Biomolecular Mechanisms, Max Planck Institut for Medical Research, Heidelberg, Germany.
authors: Daniel
authors: D
authors: Frey
authors: Biomolecular Mechanisms, Max Planck Institut for Medical Research, Heidelberg, Germany.
authors: Ilme
authors: I
authors: Schlichting
authors: Experimental Molecular Biophysics, Freie Universität Berlin, Berlin, Germany.
authors: Joachim
authors: J
authors: Heberle
mesh_terms: D020418:Algal Proteins / Q000737:chemistry* / Q000378:metabolism; D001665:Binding Sites; D056931:Cryptochromes / Q000737:chemistry* / Q000378:metabolism; D004247:DNA / Q000378:metabolism*; D007700:Kinetics; D008958:Models, Molecular; D017433:Protein Structure, Secondary; D017550:Spectroscopy, Fourier Transform Infrared; D040681:Structural Homology, Protein; D014157:Transcription Factors / Q000737:chemistry* / Q000378:metabolism
chemical_list: D020418:Algal Proteins; D056931:Cryptochromes; D014157:Transcription Factors; D004247:DNA