title: Influence of a joining helix on the BLUF domain of the YcgF photoreceptor from Escherichia coli.
abstract: BLUF-domain-comprising photoreceptors sense blue light by utilizing FAD as a chromophore. The ycgF gene product of Escherichia coli is composed of a N-terminal BLUF domain and a C-terminal EAL domain, with the latter postulated to catalyze c-di-GMP hydrolysis. The linkage between these two domains involves a predominantly helical segment. Its role on the function of the YcgF photoreceptor domain was examined by characterizing BLUF domains with and without this segment and reconstituting them with either FAD, FMN or riboflavin. The stability of the light-adapted state of the YcgF BLUF domain depends on the presence of this joining, helical segment and the adenosine diphosphate moiety of FAD. In contrast to other BLUF domains, two-dimensional (1)H,(15)N and one-dimensional (1)H NMR spectra of isotope-labeled YcgF-(1-137) revealed large conformational changes during reversion from the light- to the dark-adapted state. Based on these results the function of the joining helix in YcgF during signal transfer and the role of the BLUF domain in regulating c-di-GMP levels is discussed.
authors.affiliation: Department of Chemistry and Biochemistry, Philipps-Universität, Hans-Meerwein-Strasse, 35032 Marburg, Germany.
authors.forename: Claudia
authors.initials: C
authors.lastname: Schroeder
authors.forename: Karla
authors.initials: K
authors.lastname: Werner
authors.forename: Harm
authors.initials: H
authors.lastname: Otten
authors.forename: Steffen
authors.initials: S
authors.lastname: Krätzig
authors.forename: Harald
authors.initials: H
authors.lastname: Schwalbe
authors.forename: Lars-Oliver
authors.initials: LO
authors.lastname: Essen
mesh_terms: D000595:Amino Acid Sequence; D002850:Chromatography, Gel; D002942:Circular Dichroism; D017124:Conserved Sequence; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D015870:Gene Expression; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D010727:Phosphoric Diester Hydrolases / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment; D013053:Spectrophotometry; D013696:Temperature
chemical_list: D029968:Escherichia coli Proteins; D010727:Phosphoric Diester Hydrolases; C510176:bluF protein, E coli