Authors: Wagner, Jeremiah R.; Zhang, Junrui; Von Stetten, David; Günther, Mina; Murgida, Daniel Horacio; Mroginski, Maria Andrea; Walker, Joseph M.; Forest, Katrina T.; Hildebrandt, Peter; Vierstra, Richard D.
Publication Date: 2008.
Language: English.
Abstract:
The ability of phytochromes (Phy) to act as photointerconvertible light switches in plants and microorganisms depends on key interactions between the bilin chromophore and the apoprotein that promote bilin attachment and photointerconversion between the spectrally distinct red light-absorbing Pr conformer and far red light-absorbing Pfr conformer. Using structurally guided site-directed mutagenesis combined with several spectroscopic methods, we examined the roles of conserved amino acids within the bilin-binding domain of Deinococcus radiodurans bacteriophytochrome with respect to chromophore ligation and Pr/Pfr photoconversion. Incorporation of biliverdin IXα (BV), its structure in the Pr state, and its ability to photoisomerize to the first photocycle intermediate are insensitive to most single mutations, implying that these properties are robust with respect to small structural/electrostatic alterations in the binding pocket. In contrast, photoconversion to Pfr is highly sensitive to the chromophore environment. Many of the variants form spectrally bleached Meta-type intermediates in red light that do not relax to Pfr. Particularly important are Asp-207 and His-260, which are invariant within the Phy superfamily and participate in a unique hydrogen bond matrix involving the A, B, and C pyrrole ring nitrogens of BV and their associated pyrrole water. Resonance Raman spectroscopy demonstrates that substitutions of these residues disrupt the Pr to Pfr protonation cycle of BV with the chromophore locked in a deprotonated Meta-Rc-like photoconversion intermediate after red light irradiation. Collectively, the data show that a number of contacts contribute to the unique photochromicity of Phy-type photoreceptors. These include residues that fix the bilin in the pocket, coordinate the pyrrole water, and possibly promote the proton exchange cycle during photoconversion.
Author affiliation: Wagner, Jeremiah R.. Beloit College; Estados Unidos. University of Wisconsin; Estados Unidos
Author affiliation: Zhang, Junrui. University of Wisconsin; Estados Unidos
Author affiliation: Von Stetten, David. Technishe Universitat Berlin; Alemania
Author affiliation: Günther, Mina. Technishe Universitat Berlin; Alemania
Author affiliation: Murgida, Daniel Horacio. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Technishe Universitat Berlin; Alemania
Author affiliation: Mroginski, Maria Andrea. Technishe Universitat Berlin; Alemania
Author affiliation: Walker, Joseph M.. University of Wisconsin; Estados Unidos
Author affiliation: Forest, Katrina T.. University of Wisconsin; Estados Unidos
Author affiliation: Hildebrandt, Peter. Technishe Universitat Berlin; Alemania
Author affiliation: Vierstra, Richard D.. University of Wisconsin; Estados Unidos
Repository: CONICET Digital (CONICET). Consejo Nacional de Investigaciones Científicas y Técnicas
Authors: Von Stetten, David; Günther, Mina; Scheerer, Patrick; Murgida, Daniel Horacio; Mroginski, Maria Andrea; Krauß, Norbert; Lamparter, Tilman; Zhang, Junrui; Anstrom, David M.; Vierstra, Richard D.; Forest, Katrina T.; Hildebrandt, Peter
Publication Date: 2008.
Language: German.
Abstract:
Kristalle des Photorezeptors Phytochrom wurden zerstörungsfrei mithilfe der Resonanz‐Raman‐Spektroskopie untersucht (siehe Bild). Die Spektren der Chromophorbindungsdomäne (CBD) des Phytochroms aus Deinococcus radiodurans, von dem die dreidimensionale Struktur bestimmt wurde, zeigen im Kristall und in Lösung dieselbe Struktur. Im Unterschied zur CBD gehen Kristalle des Phytochroms aus Agrobacterium tumefaciens, das die CBD‐ und die PHY‐Domäne enthält, lichtinduziert in einen Meta‐Rc‐ähnlichen Zustand über.
Author affiliation: Von Stetten, David. Technishe Universitat Berlin; Alemania
Author affiliation: Günther, Mina. Technishe Universitat Berlin; Alemania
Author affiliation: Scheerer, Patrick. Universittsmedizin Berlin; Alemania
Author affiliation: Murgida, Daniel Horacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; Argentina
Author affiliation: Mroginski, Maria Andrea. Technishe Universitat Berlin; Alemania
Author affiliation: Krauß, Norbert. University of London; Reino Unido
Author affiliation: Lamparter, Tilman. Universitat Karlsruhe; Alemania
Author affiliation: Zhang, Junrui. University of Wisconsin; Estados Unidos
Author affiliation: Anstrom, David M.. University of Wisconsin; Estados Unidos
Author affiliation: Vierstra, Richard D.. University of Wisconsin; Estados Unidos
Author affiliation: Forest, Katrina T.. University of Wisconsin; Estados Unidos
Author affiliation: Hildebrandt, Peter. Technishe Universitat Berlin; Alemania
Repository: CONICET Digital (CONICET). Consejo Nacional de Investigaciones Científicas y Técnicas