The role of lysine acetylation of human threonyl-tRNA synthetase

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PROJECT SUMMARY Aminoacyl-tRNA synthetases (AARSs) are a family of essential enzymes for protein synthesis, which also play important roles in regulating transcription, translation, and RNA splicing. Somatic mutations of AARSs have been found in many human diseases, making them favorable targets for drug development and medical therapies. Besides mutation, proteomic studies have also identified a series of acetylated lysine residues in AARSs from cancer cells but without further studies. So there is a critical need to identify the association of AARS acetylation with cancer formation. The overall goal of this project is to study the role of lysine acetylation of one AARS, threonyl-tRNA synthetase (ThrRS) in human. Given that the homologue of ThrRS in bacteria has been shown to be regulated by acetylation, the hypothesis is that lysine acetylation affects human ThrRS functions which facilitates cancer formation. To test this hypothesis, three specific aims are proposed. Aim 1 is to identify the site- and cancer-specific effects of lysine acetylation on ThrRS functions biochemically. Aim 2 is to demonstrate the impacts of acetylation on ThrRS structurally. Aim 3 is to identify the impacts of ThrRS acetylation on global translation and translation of cancer-associated proteins, i.e. oncogenic proteins and tumor suppressor in human cell lines. Oncogenic transformation tests on normal human cells expressing acetylated ThrRS variants will be performed to find whether ThrRS acetylation is an initiator for cancer formation or a cellular adaption for cancer growth. This proposal is innovative because: First, it will be the first to study lysine acetylation of human ThrRS, and is expected to identify novel mechanisms for ThrRS-associated cancer formation. Second, to address the problem that the classic glutamine-substitution method for acetylation studies is not always effective, the genetic code expansion approach will be applied in this proposal to co-translationally incorporate acetyllysine at controlled sites in order to produce site-specifically acetylated ThrRS variants which have been identified in cancer cells. The proposed research is significant because it will provide solid evidence for the association of ThrRS acetylation with cancer formation. Ultimately, the proposed studies on ThrRS acetylation are expected to identify novel targets for cancer diagnosis and treatment. Specific for the AREA program, the research team for this project will be composed primarily of undergraduate students including those from underrepresented groups. Both well-established methods and new approaches will be applied in this proposal to make the project promising, and in the meantime, to strengthen students’ research experiences.