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The Effect of tRNA^[Ser]Sec Isopentenylation on Selenoprotein Expression

Lookup NU author(s): Professor Bobby McFarlandORCiD, Professor Robert Taylor

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This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).

Abstract

© 2021 by the authors. Licensee MDPI, Basel, Switzerland.Transfer RNA[Ser]Sec carries multiple post-transcriptional modifications. The A37G mutation in tRNA[Ser]Sec abrogates isopentenylation of base 37 and has a profound effect on selenoprotein expression in mice. Patients with a homozygous pathogenic p.R323Q variant in tRNA-isopentenyltransferase (TRIT1) show a severe neurological disorder, and hence we wondered whether selenoprotein expression was impaired. Patient fibroblasts with the homozygous p.R323Q variant did not show a general decrease in selenoprotein expression. However, recombinant human TRIT1R323Q had significantly diminished activities towards several tRNA substrates in vitro. We thus engineered mice conditionally deficient in Trit1 in hepatocytes and neurons. Mass-spectrometry revealed that hypermodification of U34 to mcm5Um occurs independently of isopentenylation of A37 in tRNA[Ser]Sec . Western blotting and75Se metabolic labeling showed only moderate effects on selenoprotein levels and75Se incorporation. A detailed analysis of Trit1-deficient liver using ribosomal profiling demonstrated that UGA/Sec re-coding was moderately affected in Selenop, Txnrd1, and Sephs2, but not in Gpx1. 2′O-methylation of U34 in tRNA[Ser]Sec depends on FTSJ1, but does not affect UGA/Sec re-coding in selenoprotein translation. Taken together, our results show that a lack of isopentenylation of tRNA[Ser]Sec affects UGA/Sec read-through but differs from a A37G mutation.

Publication metadata

Author(s): Fradejas-Villar N, Bohleber S, Zhao W, Reuter U, Kotter A, Helm M, Knoll R, McFarland R, Taylor RW, Mo Y, Miyauchi K, Sakaguchi Y, Suzuki T, Schweizer U

Publication type: Article

Publication status: Published

Journal: International Journal of Molecular Sciences

Year: 2021

Volume: 22

Issue: 21

Online publication date: 23/10/2021

Acceptance date: 19/10/2021

Date deposited: 19/07/2022

ISSN (print): 1661-6596

ISSN (electronic): 1422-0067

Publisher: MDPI AG

URL: https://doi.org/10.3390/ijms222111454

DOI: 10.3390/ijms222111454

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