Gain-of-function mutational activation of human tRNA synthetase procytokine.
Disease-causing mutations occur in genes for aminoacyl tRNA synthetases. That some mutations are dominant suggests a gain of function. Native tRNA synthetases, such as tyrosyl-tRNA synthetase (TyrRS) and tryptophanyl-tRNA synthetase, catalyze aminoacylation and are also procytokines that are activated by natural fragmentation. In principle, however, gain-of-function phenotypes could arise from mutational activation of synthetase procytokines. From crystal structure analysis, we hypothesized that a steric block of a critical Glu-Leu-Arg (ELR) motif in full-length TyrRS suppresses the cytokine activity of a natural fragment. To test this hypothesis, we attempted to uncover ELR in the procytokine by mutating a conserved tyrosine (Y341) that tethers ELR. Site-specific proteolytic cleavage and small-angle X-ray scattering established subtle opening of the structure by the mutation. Strikingly, four different assays demonstrated mutational activation of cytokine functions. The results prove the possibilities for constitutive gain-of-function mutations in tRNA synthetases.
Yang
Xiang-Lei
XL
Department of Molecular Biology and Chemistry and the Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA. xlyang@scripps.edu
Kapoor
Mili
M
Otero
Francella J
FJ
Slike
Bonnie M
BM
Tsuruta
Hiro
H
Frausto
Ricardo
R
Bates
Alison
A
Ewalt
Karla L
KL
Cheresh
David A
DA
Schimmel
Paul
P
D020816:Amino Acid Motifs / Q000235:genetics; D019943:Amino Acid Substitution; D000818:Animals; D002417:Cattle; D002465:Cell Movement / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D002634:Chemotaxis, Leukocyte / Q000187:drug effects; D002642:Chick Embryo; D016207:Cytokines / Q000378:metabolism*; D042783:Endothelial Cells / Q000166:cytology / Q000187:drug effects; D006801:Humans; D007963:Leukocytes, Mononuclear / Q000166:cytology / Q000187:drug effects; D051379:Mice; D008819:Mice, Nude; D008958:Models, Molecular; D009154:Mutation; D018919:Neovascularization, Physiologic / Q000187:drug effects; D010446:Peptide Fragments / Q000737:chemistry / Q000494:pharmacology; D010447:Peptide Hydrolases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D053838:Scattering, Small Angle; D014448:Tyrosine-tRNA Ligase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D014961:X-Ray Diffraction
D016207:Cytokines; D010446:Peptide Fragments; D010447:Peptide Hydrolases; D014448:Tyrosine-tRNA Ligase