title: Dispersed disease-causing neomorphic mutations on a single protein promote the same localized conformational opening.
abstract: The question of how dispersed mutations in one protein engender the same gain-of-function phenotype is of great interest. Here we focus on mutations in glycyl-tRNA synthetase (GlyRS) that cause an axonal form of Charcot-Marie-Tooth (CMT) diseases, the most common hereditary peripheral neuropathies. Because the disease phenotype is dominant, and not correlated with defects in the role of GlyRS in protein synthesis, the mutant proteins are considered to be neomorphs that gain new functions from altered protein structure. Given that previous crystal structures showed little conformational difference between dimeric wild-type and CMT-causing mutant GlyRSs, the mutant proteins were investigated in solution by hydrogen-deuterium exchange (monitored by mass spectrometry) and small-angle X-ray scattering to uncover structural changes that could be suppressed by crystal packing interactions. Significantly, each of five spatially dispersed mutations induced the same conformational opening of a consensus area that is mostly buried in the wild-type protein. The identified neomorphic surface is thus a candidate for making CMT-associated pathological interactions, and a target for disease correction. Additional result showed that a helix-turn-helix WHEP domain that was appended to GlyRS in metazoans can regulate the neomorphic structural change, and that the gain of function of the CMT mutants might be due to the loss of function of the WHEP domain as a regulator. Overall, the results demonstrate how spatially dispersed and seemingly unrelated mutations can perpetrate the same localized effect on a protein.
authors: Departments of Chemical Physiology and Molecular Biology, The Scripps Research Institute, La Jolla, CA 92037, USA.
authors: Weiwei
authors: W
authors: He
authors: Hui-Min
authors: HM
authors: Zhang
authors: Yeeting E
authors: YE
authors: Chong
authors: Min
authors: M
authors: Guo
authors: Alan G
authors: AG
authors: Marshall
authors: Xiang-Lei
authors: XL
authors: Yang
mesh_terms: D000595:Amino Acid Sequence; D055592:Biophysical Phenomena; D002607:Charcot-Marie-Tooth Disease / Q000201:enzymology / Q000235:genetics; D041961:Deuterium Exchange Measurement; D019281:Dimerization; D006032:Glycine-tRNA Ligase / Q000737:chemistry / Q000235:genetics; D006801:Humans; D013058:Mass Spectrometry; D008958:Models, Molecular; D008969:Molecular Sequence Data; D050505:Mutant Proteins / Q000737:chemistry* / Q000235:genetics*; D009154:Mutation; D011487:Protein Conformation; D054730:Protein Interaction Domains and Motifs; D020836:Protein Structure, Quaternary; D053838:Scattering, Small Angle; D014961:X-Ray Diffraction
chemical_list: D050505:Mutant Proteins; D006032:Glycine-tRNA Ligase