8fxt

Escherichia coli periplasmic Glucose-Binding Protein glucose complex: Acrylodan conjugate attached at W183C

spinqualitylabelsall models 8fxt, resolution 1.53Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 8fxt is a 1 chain structure with sequence from Escherichia coli. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 1.53Å Ligands: BGC, CA, GLC, YDM Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function MGLB_ECOLI Part of the ABC transporter complex MglABC involved in galactose/methyl galactoside import (Probable). In addition, binds D-galactose and D-glucose and plays a role in the chemotaxis towards these two sugars by interacting with the Trg chemoreceptor (PubMed:3057628, PubMed:4927373). Chemotaxis requires MglB, but not MglA or MglC (PubMed:6294056). Publication Abstract from PubMed Fluorescent labeling of proteins is a powerful tool for probing structure-function relationships with many biosensing applications. Structure-based rules for systematically designing fluorescent biosensors require understanding ligand-mediated fluorescent response mechanisms which can be challenging to establish. We installed thiol-reactive derivatives of the naphthalene-based fluorophore Prodan into bacterial periplasmic glucose-binding proteins. Glucose binding elicited paired color exchanges in the excited and ground states of these conjugates. X-ray structures and mutagenesis studies established that glucose-mediated color switching arises from steric interactions that couple protein conformational changes to twisting of the Prodan carbonyl relative to its naphthalene plane. Mutations of residues contacting the carbonyl can optimize color switching by altering fluorophore conformational equilibria in the apo and glucose-bound proteins. A commonly accepted view is that Prodan derivatives report on protein conformations via solvatochromic effects due to changes in the dielectric of their local environment. Here we show that instead Prodan carbonyl twisting controls color switching. These insights enable structure-based biosensor design by coupling ligand-mediated protein conformational changes to internal chromophore twists through specific steric interactions between fluorophore and protein. Chromophore carbonyl twisting in fluorescent biosensors encodes direct readout of protein conformations with multicolor switching.,Allert MJ, Kumar S, Wang Y, Beese LS, Hellinga HW Commun Chem. 2023 Aug 19;6(1):168. doi: 10.1038/s42004-023-00982-7. PMID:37598249 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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