The mechanism of β-N-methylamino-l-alanine inhibition of tRNA aminoacylation and its impact on misincorporation | Health & Environmental Research Online (HERO)

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Citation
Tags

HERO ID

7425575

Reference Type

Journal Article

Title

The mechanism of β-N-methylamino-l-alanine inhibition of tRNA aminoacylation and its impact on misincorporation

Author(s)

Han, NC; Bullwinkle, TJ; Loeb, KF; Faull, KF; Mohler, K; Rinehart, J; Ibba, M; ,

Year

2020

Is Peer Reviewed?

Yes

Journal

Journal of Biological Chemistry
ISSN: 0021-9258
EISSN: 1083-351X

Publisher

American Society for Biochemistry and Molecular Biology Inc.

Volume

295

Issue

Page Numbers

1402-1410

Language

English

PMID

31862734

DOI

10.1074/jbc.RA119.011714

Web of Science Id

WOS:000513822300022

URL

http://www.jbc.org/lookup/doi/10.1074/jbc.RA119.011714
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Abstract

β-N-methylamino-l-alanine (BMAA) is a nonproteinogenic amino acid that has been associated with neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS) and Alzheimer's disease (AD). BMAA has been found in human protein extracts; however, the mechanism by which it enters the proteome is still unclear. It has been suggested that BMAA is misincorporated at serine codons during protein synthesis, but direct evidence of its cotranslational incorporation is currently lacking. Here, using LC-MS-purified BMAA and several biochemical assays, we sought to determine whether any aminoacyl-tRNA synthetase (aaRS) utilizes BMAA as a substrate for aminoacylation. Despite BMAA's previously predicted misincorporation at serine codons, following a screen for amino acid activation in ATP/PPi exchange assays, we observed that BMAA is not a substrate for human seryl-tRNA synthetase (SerRS). Instead, we observed that BMAA is a substrate for human alanyl-tRNA synthetase (AlaRS) and can form BMAA-tRNAAla by escaping from the intrinsic AlaRS proofreading activity. Furthermore, we found that BMAA inhibits both the cognate amino acid activation and the editing functions of AlaRS. Our results reveal that, in addition to being misincorporated during translation, BMAA may be able to disrupt the integrity of protein synthesis through multiple different mechanisms.

Keywords

aminoacyl tRNA synthetase; protein synthesis; translation; transfer RNA (tRNA); amino acid; beta-N-methylamino-L-alanine (BMAA); nonproteinogenic amino acid (NPA); alanyl-tRNA synthetase (AlaRS); amyotrophic lateral sclerosis (ALS); neurodegeneration and cyanotoxin