6i21

Flavin Analogue Sheds Light on Light-Oxygen-Voltage Domain Mechanism

spinqualitylabelsall models 6i21, resolution 1.50Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 6i21 is a 1 chain structure with sequence from Ochromonas danica. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 1.5Å Ligands: CL, EDO, FMN, MG, PEG Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function C5NSW6_OCHDN Publication Abstract from PubMed Light-oxygen-voltage (LOV) domains are increasingly used to engineer photoresponsive biological systems. While the photochemical cycle is well documented, the allosteric mechanism by which formation of a cysteinyl-flavin adduct leads to activation is unclear. Via replacement of flavin mononucleotide (FMN) with 5-deazaflavin mononucleotide (5dFMN) in the Aureochrome1a (Au1a) transcription factor from Ochromonas danica, a thermally stable cysteinyl-5dFMN adduct was generated. High-resolution crystal structures (<2 A) under different illumination conditions with either FMN or 5dFMN chromophores reveal three conformations of the highly conserved glutamine 293. An allosteric hydrogen bond network linking the chromophore via Gln293 to the auxiliary A'alpha helix is observed. With FMN, a "flip" of the Gln293 side chain occurs between dark and lit states. 5dFMN cannot hydrogen bond through the C5 position and proved to be unable to support Au1a domain dimerization. Under blue light, the Gln293 side chain instead "swings" away in a conformation distal to the chromophore and not previously observed in existing LOV domain structures. Together, the multiple side chain conformations of Gln293 and functional analysis of 5dFMN provide new insight into the structural requirements for LOV domain activation. A Noncanonical Chromophore Reveals Structural Rearrangements of the Light-Oxygen-Voltage Domain upon Photoactivation.,Kalvaitis ME, Johnson LA, Mart RJ, Rizkallah P, Allemann RK Biochemistry. 2019 May 17. doi: 10.1021/acs.biochem.9b00255. PMID:31082213 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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