9p4d

Crystal Structure of Engineered glutamine binding protein and a Gd-DOTA ligand - Gln bound

spinqualitylabelsall models 9p4d, resolution 2.57Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 9p4d is a 6 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 2.57Å Ligands: A1C21, ACT, GD3, GLN, GOL, SO4 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function C3THM2_ECOLX Publication Abstract from PubMed Magnetic resonance imaging (MRI) is widely used to visualize disease, and image quality can be improved through use of MRI contrast agents. Currently available agents produce a signal based solely on spatial distribution, but modern metabolic profiling has uncovered a variety of biomarkers for disease. For example, tumors greatly increase their uptake and catabolism of glutamine (Gln), leading to modified local concentration. Our laboratory previously developed a switchable artificial metalloprotein (swArM) platform in which Gln-binding causes a protein conformational change that modifies the physicochemical environment of an installed metallocofactor. Installing MRI-active metallocofactors within swArMs, we present a proof-of-concept approch toward the development of an analyte-responsive MRI contrast agent. To develop these swArMs, we tested several MRI-active metals (Gd(3+), Dy(3+)), chelating ligands (DOTA, DTPA, NOTA), and attachment sites, as well as the impacts of peripheral mutations on the Gln-responsive signal. In each case, metal content was analytically defined, and Gln-binding affinity was determined by isothermal titration calorimetry. Circular dichroism was used to verify that our swArMs could still undergo the conformational change. X-ray diffraction structures of the apo- and holo-swArMs further revealed that the metallocofactor is significantly solvent-exposed in both conformations, but exhibits additional interactions with the protein in the holo-state coinciding with the observed increase in T (2) relaxivity of approximately 60% upon Gln-binding. Development of a glutamine-responsive MRI contrast agent.,Wilson CA, Bruchs AT, Fatima S, Boggs DG, Bridwell-Rabb J, Olshansky L Chem Sci. 2025 Nov 20. doi: 10.1039/d5sc05987a. PMID:41395538 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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