NMR Analysis of Apo Glutamine‐Binding Protein Exposes Challenges in the Study of Interdomain Dynamics. Issue 47 (11th October 2019)

• Record Type: Journal Article
• Authors: Kooshapur, Hamed; Ma, Junhe; Tjandra, Nico; Bermejo, Guillermo A.
• Is Part Of: Angewandte Chemie international edition. Volume 58:Issue 47(2019)
• Page Start: 16899
• Page End: 16902
• Publication Date: 2019-10-11
• Subjects: interdomain dynamics -- nuclear magnetic resonance -- paramagnetic relaxation enhancement -- periplasmic binding protein -- residual dipolar coupling; Chemistry -- Periodicals; 540
• DOI: 10.1002/anie.201911015
• Languages: English
• ISSNs: 1433-7851

Abstract

Abstract: Glutamine‐binding protein (GlnBP) displays an apo, "open" and a holo, "closed" crystal form, mutually related by a rigid‐body reorientation of its domains. A fundamental question about such large‐scale conformational transitions, whether the closed state exists in the absence of ligand, is controversial in the case of GlnBP. NMR observations have indicated no evidence of the closed form, whereas experimentally validated computations have suggested a remarkable ca. 40 % population. Herein, a paramagnetic NMR strategy designed to detect the putative apo‐closed species shows that a major population of the latter is highly improbable. Further, NMR residual dipolar couplings collected under three anisotropic conditions do not reveal differential domain alignment and establish that the average solution conformation is satisfied by the apo‐open crystal structure. Our results indicate that the computational prediction of large‐scale interdomain motions is not trivial and may lead to erroneous conclusions without proper experimental validation. Abstract : NMR paramagnetic relaxation enhancements and residual dipolar couplings indicate that apo glutamine‐binding protein strongly favors an open conformation in solution. The findings expose serious problems in the computational study of interdomain protein motions.