Abstract
Backbone assignments for the isolated α-subunit of Salmonella typhimurium tryptophan synthase (TS) are reported based on triple resonance solution-state NMR experiments on a uniformly 2H,13C,15N-labeled sample. From the backbone chemical shifts, secondary structure and random coil index order parameters (RCI-S2) are predicted. Titration with the 3-indole-d-glycerol 3′-phosphate analog, N-(4′-trifluoromethoxybenzenesulfonyl)-2-aminoethyl phosphate (F9), leads to chemical shift perturbations indicative of conformational changes from which an estimate of the dissociation constant is obtained. Comparisons of the backbone chemical-shifts, RCI-S2 values, and site-specific relaxation times with and without F9 reveal allosteric changes including modulation in secondary structures and loop rigidity induced upon ligand binding. A comparison is made to the X-ray crystal structure of the α-subunit in the full TS αββα bi-enzyme complex and to two new X-ray crystal structures of the isolated TS α-subunit reported in this work.
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Research reported in this publication was supported in part by NSF Grant CHE1710671 to L.F. and NIH Grant GM097569 to L.J.M. and M.F.D.
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Sakhrani, V.V., Hilario, E., Caulkins, B.G. et al. Backbone assignments and conformational dynamics in the S. typhimurium tryptophan synthase α-subunit from solution-state NMR. J Biomol NMR 74, 341–354 (2020). https://doi.org/10.1007/s10858-020-00320-2
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DOI: https://doi.org/10.1007/s10858-020-00320-2