Lysyl-tRNA synthetase (LysRS), a component of the translation apparatus, is released from the cytoplasmic multi-tRNA synthetase complex (MSC) to activate the transcription factor MITF in stimulated mast cells through undefined mechanisms. Here we show that Ser207 phosphorylation provokes a new conformer of LysRS that inactivates its translational function but activates its transcriptional function. The crystal structure of an MSC subcomplex established that LysRS is held in the MSC by binding to the N terminus of the scaffold protein p38/AIMP2. Phosphorylation-created steric clashes at the LysRS domain interface disrupt its binding grooves for p38/AIMP2, releasing LysRS and provoking its nuclear translocation. This alteration also exposes the C-terminal domain of LysRS to bind to MITF and triggers LysRS-directed production of the second messenger Ap4A that activates MITF. Thus our results establish that a single conformational change triggered by phosphorylation leads to multiple effects driving an exclusive switch of LysRS function from translation to transcription.
Bibliographical noteFunding Information:
We thank John Cleveland for critical review and editing of the manuscript. Use of the Advanced Photon Source and Advanced Light Source was supported by the U.S. Department of Energy under contract number DE-AC02-06CH11357, DE-AC02-05CH11231. This work was supported in part by grants from NIH (GM088278 [X.-L.Y.], GM23562 [P.S.], GM78359 [A.G.M.], GM100136 [M.G.]); by NSF Division of Materials Research through DMR-06-54118 (A.G.M.); by a fellowship from the National Foundation for Cancer Research; by the Global Frontier Project (NRF-M1AXA002-2012M3A6A4054273) and the WCU project (R31-2008-000-10103-0) of the Ministry of Education, Science, and Technology, Korea (S.K.); by the Israel Science Foundation, the United States Binational Science Foundation, the National Research Foundation of Singapore (HUJ-CREATE), the German-Israel Foundation for Scientific Research and Development, the Cooperation Program in Cancer Research of the Deutsches Krebsforschungszentrum (DKFZ), and Israel’s Ministry of Science and Technology (MOST) (E.R.); and by funding from the state of Florida to Scripps Florida (M.G.). E.R. and M.G. designed the experiments. Y.O.-B., P.F., S.P.B., H.-M.Z., J.W., I.R., R.S., J.S., A.D., and J.P. performed the experiments. Y.O.-B., P.F., S.P.B., H-M.Z., H.N., and M.G. analyzed the data. Y.O.-B., P.F., S.P.B., H.-M.Z., S.K., A.G.M., X.-L.Y., P.S., E.R., and M.G. wrote the paper. All authors discussed the results and commented on the manuscript.
All Science Journal Classification (ASJC) codes
- Molecular Biology
- Cell Biology