title: Structure and function of a short LOV protein from the marine phototrophic bacterium Dinoroseobacter shibae.
abstract: BACKGROUND
  Light, oxygen, voltage (LOV) domains are widely distributed in plants, algae, fungi, bacteria, and represent the photo-responsive domains of various blue-light photoreceptor proteins. Their photocycle involves the blue-light triggered adduct formation between the C(4a) atom of a non-covalently bound flavin chromophore and the sulfur atom of a conserved cysteine in the LOV sensor domain. LOV proteins show considerable variation in the structure of N- and C-terminal elements which flank the LOV core domain, as well as in the lifetime of the adduct state.
  
  
  RESULTS
  Here, we report the photochemical, structural and functional characterization of DsLOV, a LOV protein from the photoheterotrophic marine α-proteobacterium Dinoroseobacter shibae which exhibits an average adduct state lifetime of 9.6 s at 20°C, and thus represents the fastest reverting bacterial LOV protein reported so far. Mutational analysis in D. shibae revealed a unique role of DsLOV in controlling the induction of photopigment synthesis in the absence of blue-light. The dark state crystal structure of DsLOV determined at 1.5 Å resolution reveals a conserved core domain with an extended N-terminal cap. The dimer interface in the crystal structure forms a unique network of hydrogen bonds involving residues of the N-terminus and the β-scaffold of the core domain. The structure of photoexcited DsLOV suggests increased flexibility in the N-cap region and a significant shift in the Cα backbone of β strands in the N- and C-terminal ends of the LOV core domain.
  
  
  CONCLUSIONS
  The results presented here cover the characterization of the unusual short LOV protein DsLOV from Dinoroseobacter shibae including its regulatory function, extremely fast dark recovery and an N-terminus mediated dimer interface. Due to its unique photophysical, structural and regulatory properties, DsLOV might thus serve as an alternative model system for studying light perception by LOV proteins and physiological responses in bacteria.
authors.affiliation: Institute of Molecular Enzyme Technology, Heinrich-Heine-Universität Düsseldorf, Forschungszentrum Jülich, D-52425, Jülich, Germany. s.endres@fz-juelich.de.
authors.forename: Stephan
authors.initials: S
authors.lastname: Endres
authors.affiliation: Institute of Complex Systems, ICS-6: Structural Biochemistry, Forschungszentrum Jülich, D-52425, Jülich, Germany. j.granzin@fz-juelich.de.
authors.forename: Joachim
authors.initials: J
authors.lastname: Granzin
authors.affiliation: Institute of Molecular Enzyme Technology, Heinrich-Heine-Universität Düsseldorf, Forschungszentrum Jülich, D-52425, Jülich, Germany. f.circolone@fz-juelich.de.
authors.forename: Franco
authors.initials: F
authors.lastname: Circolone
authors.affiliation: Juelich Centre for Neutron Science JCNS (JCNS-1) & Institute for Complex Systems (ICS-1), Forschungszentrum Jülich, D-52425, Jülich, Germany. a.stadler@fz-juelich.de.
authors.forename: Andreas
authors.initials: A
authors.lastname: Stadler
authors.affiliation: Institute of Molecular Enzyme Technology, Heinrich-Heine-Universität Düsseldorf, Forschungszentrum Jülich, D-52425, Jülich, Germany. u.krauss@fz-juelich.de.
authors.forename: Ulrich
authors.initials: U
authors.lastname: Krauss
authors.affiliation: Institute of Molecular Enzyme Technology, Heinrich-Heine-Universität Düsseldorf, Forschungszentrum Jülich, D-52425, Jülich, Germany. t.drepper@fz-juelich.de.
authors.forename: Thomas
authors.initials: T
authors.lastname: Drepper
authors.affiliation: Institute of Molecular Enzyme Technology, Heinrich-Heine-Universität Düsseldorf, Forschungszentrum Jülich, D-52425, Jülich, Germany. v.svensson@fz-juelich.de.
authors.forename: Vera
authors.initials: V
authors.lastname: Svensson
authors.affiliation: Institute of Molecular Enzyme Technology, Heinrich-Heine-Universität Düsseldorf, Forschungszentrum Jülich, D-52425, Jülich, Germany. e.knieps@fz-juelich.de.
authors.forename: Esther
authors.initials: E
authors.lastname: Knieps-Grünhagen
authors.affiliation: Institute of Molecular Enzyme Technology, Heinrich-Heine-Universität Düsseldorf, Forschungszentrum Jülich, D-52425, Jülich, Germany. a.wirtz@fz-juelich.de.
authors.forename: Astrid
authors.initials: A
authors.lastname: Wirtz
authors.affiliation: Institute of Complex Systems, ICS-6: Structural Biochemistry, Forschungszentrum Jülich, D-52425, Jülich, Germany. a.cousin@fz-juelich.de.
authors.forename: Anneliese
authors.initials: A
authors.lastname: Cousin
authors.affiliation: Institute for Microbiology, Technische Universität Braunschweig, D-38106, Braunschweig, Germany. p.tielen@tu-bs.de.
authors.forename: Petra
authors.initials: P
authors.lastname: Tielen
authors.affiliation: Institute of Complex Systems, ICS-6: Structural Biochemistry, Forschungszentrum Jülich, D-52425, Jülich, Germany. D.Willbold@fz-juelich.de.|Institute of Physical Biology, Heinrich-Heine-Universität Düsseldorf, D-40225, Düsseldorf, Germany. D.Willbold@fz-juelich.de.
authors.forename: Dieter
authors.initials: D
authors.lastname: Willbold
authors.affiliation: Institute of Molecular Enzyme Technology, Heinrich-Heine-Universität Düsseldorf, Forschungszentrum Jülich, D-52425, Jülich, Germany. karl-erich.jaeger@fz-juelich.de.|Institute of Bio- and Geosciences, IBG-1: Biotechnology, Forschungszentrum Jülich, D-52425, Jülich, Germany. karl-erich.jaeger@fz-juelich.de.
authors.forename: Karl-Erich
authors.initials: KE
authors.lastname: Jaeger
authors.affiliation: Institute of Complex Systems, ICS-6: Structural Biochemistry, Forschungszentrum Jülich, D-52425, Jülich, Germany. r.batra-safferling@fz-juelich.de.
authors.forename: Renu
authors.initials: R
authors.lastname: Batra-Safferling
mesh_terms: D059001:Aquatic Organisms / Q000737:chemistry / Q000254:growth & development; D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism*; D003460:Crystallization / Q000379:methods; D018360:Crystallography, X-Ray; D004252:DNA Mutational Analysis; D008958:Models, Molecular; D052817:Phototrophic Processes; D010860:Pigments, Biological / Q000378:metabolism; D011487:Protein Conformation; D055503:Protein Multimerization; D041902:Rhodobacteraceae / Q000737:chemistry* / Q000254:growth & development
chemical_list: D001426:Bacterial Proteins; D010860:Pigments, Biological