{"doi":"10.1016/j.jbc.2021.101203","title":"Disease-associated mutations in a bifunctional aminoacyl-tRNA synthetase gene elicit the integrated stress response","abstract":"Aminoacyl-tRNA synthetases (ARSs) catalyze the charging of specific amino acids onto cognate tRNAs, an essential process for protein synthesis. Mutations in ARSs are frequently associated with a variety of human diseases. The human EPRS1 gene encodes a bifunctional glutamyl-prolyl-tRNA synthetase (EPRS) with two catalytic cores and appended domains that contribute to nontranslational functions. In this study, we report compound heterozygous mutations in EPRS1, which lead to amino acid substitutions P14R and E205G in two patients with diabetes and bone diseases. While neither mutation affects tRNA binding or association of EPRS with the multisynthetase complex, E205G in the glutamyl-tRNA synthetase (ERS) region of EPRS is defective in amino acid activation and tRNAGlu charging. The P14R mutation induces a conformational change and altered tRNA charging kinetics in vitro. We propose that the altered catalytic activity and conformational changes in the EPRS variants sensitize patient cells to stress, triggering an increased integrated stress response (ISR) that diminishes cell viability. Indeed, patient-derived cells expressing the compound heterozygous EPRS show heightened induction of the ISR, suggestive of disruptions in protein homeostasis. These results have important implications for understanding ARS-associated human disease mechanisms and development of new therapeutics. Aminoacyl-tRNA synthetases (ARSs) catalyze the charging of specific amino acids onto cognate tRNAs, an essential process for protein synthesis. Mutations in ARSs are frequently associated with a variety of human diseases. The human EPRS1 gene encodes a bifunctional glutamyl-prolyl-tRNA synthetase (EPRS) with two catalytic cores and appended domains that contribute to nontranslational functions. In this study, we report compound heterozygous mutations in EPRS1, which lead to amino acid substitutions P14R and E205G in two patients with diabetes and bone diseases. While neither mutation affects tRNA binding or association of EPRS with the multisynthetase complex, E205G in the glutamyl-tRNA synthetase (ERS) region of EPRS is defective in amino acid activation and tRNAGlu charging. The P14R mutation induces a conformational change and altered tRNA charging kinetics in vitro. We propose that the altered catalytic activity and conformational changes in the EPRS variants sensitize patient cells to stress, triggering an increased integrated stress response (ISR) that diminishes cell viability. Indeed, patient-derived cells expressing the compound heterozygous EPRS show heightened induction of the ISR, suggestive of disruptions in protein homeostasis. These results have important implications for understanding ARS-associated human disease mechanisms and development of new therapeutics. Aminoacyl-tRNA synthetases (ARSs) are essential enzymes for protein synthesis across all domains of life, ensuring translational fidelity and maintenance of protein homeostasis by aminoacylating tRNAs with their cognate amino acids. For each amino acid, with a few exceptions in some bacteria and archaea, a specific ARS catalyzes tRNA aminoacylation in two steps: (1) amino acid activation and formation of an aminoacyl-adenylate (aa-AMP) and (2) transfer of the amino acid onto the 3′ end of tRNA (1Rubio Gomez M.A. Ibba M. Aminoacyl-tRNA synthetases.RNA. 2020; 26: 910-936Crossref PubMed Scopus (29) Google Scholar). In addition to a catalytic domain that directs the aminoacylation or charging reaction, the majority of ARSs contain an anticodon-binding domain that interacts specifically with the cognate tRNA substrate. Many eukaryotic ARSs have appended domains with no apparent function in tRNA charging (2Guo M. Schimmel P. Essential nontranslational functions of tRNA synthetases.Nat. Chem. Biol. 2013; 9: 145-153Crossref PubMed Scopus (241) Google Scholar). For example, human glutamyl-prolyl tRNA synthetase (EPRS) is a unique bifunctional ARS, consisting of glutamyl-tRNA synthetase (ERS) ","journal":"Journal of Biological Chemistry","year":2021,"id":171951,"datarank":0.49983067652628066,"base_score":3.332204510175204,"endowment":3.332204510175204,"self_citation_contribution":0.49983067652628066,"citation_network_contribution":0.0,"self_endowment_contribution":0.49983067652628066,"citer_contribution":0.0,"corpus_percentile":null,"corpus_rank":null,"citation_count":27,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.9515,"is_data_producer":false,"deposit_databanks":null,"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2021-01-01","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":708127,"name":"Sheree A. Wek","orcid":null,"position":1,"is_corresponding":false},{"id":708128,"name":"Nathan Kudlapur","orcid":null,"position":2,"is_corresponding":false},{"id":404741,"name":"William A. Cantara","orcid":"0000-0002-3214-7635","position":3,"is_corresponding":false},{"id":481345,"name":"Marina Bakhtina","orcid":"0000-0003-0322-1901","position":4,"is_corresponding":false},{"id":337624,"name":"Ronald C. Wek","orcid":"0000-0002-2087-5504","position":5,"is_corresponding":false},{"id":377519,"name":"Karin Musier‐Forsyth","orcid":null,"position":6,"is_corresponding":false},{"id":707415,"name":"Danni Jin","orcid":"0000-0002-2878-9950","position":0,"is_corresponding":true}],"reference_count":66,"raw_metadata":{"citation_network_status":"fetched"},"created_at":"2026-07-18T23:46:37.150824Z","pmid":"34537243","pmcid":null,"fwci":null,"citation_percentile":null,"influential_citations":0,"oa_status":null,"license":null,"views":0,"total_file_size_bytes":0,"version_count":0,"fair_f":null,"fair_a":null,"fair_i":null,"fair_r":null,"fair_zscore":null,"fair_rationale":null,"fair_model":null,"fair_agent_version":null,"fair_fulltext_source":null,"fair_has_llm":null,"fair_computed_at":null,"clinical_trials":[],"software_tools":[],"db_accessions":[],"linked_datasets":[],"topics":[]}