title: LOV takes a pick: thermodynamic and structural aspects of the flavin-LOV-interaction of the blue-light sensitive photoreceptor YtvA from Bacillus subtilis.
abstract: LOV domains act as versatile photochromic switches servicing multiple effector domains in a variety of blue light sensing photoreceptors abundant in a multitude of organisms from all kingdoms of life. The perception of light is realized by a flavin chromophore that upon illumination reversibly switches from the non-covalently bound dark-state to a covalently linked flavin-LOV adduct. It is usually assumed that most LOV domains preferably bind FMN, but heterologous expression frequently results in the incorporation of all natural occurring flavins, i.e. riboflavin, FMN and FAD. Over recent years, the structures, photochemical properties, activation mechanisms and physiological functions of a multitude of LOV proteins have been studied intensively, but little is known about its affinities to physiologically relevant flavins or the thermodynamics of the flavin-LOV interaction. We have investigated the interaction of the LOV domain of the well characterized bacterial photoreceptor YtvA with riboflavin, FMN and FAD by ITC experiments providing binding constants and thermodynamic profiles of these interactions. For this purpose, we have developed a protocol for the production of the apo forms of YtvA and its isolated LOV domain and we demonstrate that the latter can be used as a molecular probe for free flavins in cell lysates. Furthermore, we show here using NMR spectroscopic techniques and Analytical Ultracentrifugation that the flavin moiety stabilizes the conformation of the LOV domain and that dimerization of YtvA is caused not only by intermolecular LOV-LOV but also by STAS-STAS contacts.
authors.affiliation: Department of Structural Biology, Leibniz-Institut für Molekulare Pharmakologie, Berlin, Germany ; Department of Chemistry and Biochemistry, Freie Universität Berlin, Berlin, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Dorn
authors.forename: Marcel
authors.initials: M
authors.lastname: Jurk
authors.forename: Anne
authors.initials: A
authors.lastname: Wartenberg
authors.forename: Aaron
authors.initials: A
authors.lastname: Hahn
authors.forename: Peter
authors.initials: P
authors.lastname: Schmieder
mesh_terms: D001059:Apoproteins / Q000737:chemistry / Q000378:metabolism; D001412:Bacillus subtilis / Q000378:metabolism*; D005486:Flavin Mononucleotide / Q000737:chemistry / Q000378:metabolism; D005182:Flavin-Adenine Dinucleotide / Q000737:chemistry / Q000378:metabolism; D005415:Flavins / Q000737:chemistry* / Q000378:metabolism; D008027:Light; D019906:Nuclear Magnetic Resonance, Biomolecular; D020283:Photoreceptors, Microbial / Q000737:chemistry* / Q000378:metabolism; D011485:Protein Binding; D054730:Protein Interaction Domains and Motifs; D055503:Protein Multimerization
chemical_list: D001059:Apoproteins; D005415:Flavins; D020283:Photoreceptors, Microbial; D005182:Flavin-Adenine Dinucleotide; D005486:Flavin Mononucleotide