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

Autor: Han NC; Department of Microbiology, The Ohio State University, Columbus, Ohio 43220., Bullwinkle TJ; Department of Microbiology, The Ohio State University, Columbus, Ohio 43220., Loeb KF; Department of Microbiology, The Ohio State University, Columbus, Ohio 43220., Faull KF; Pasarow Mass Spectrometry Laboratory, Jane and Terry Semel Institute for Neuroscience and Human Behavior, Department of Psychiatry & Biobehavioral Sciences, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, California 90024-1759., Mohler K; Department of Cellular and Molecular Physiology, Yale University, New Haven, Connecticut 06520.; Systems Biology Institute, Yale University, New Haven, Connecticut 06520., Rinehart J; Department of Cellular and Molecular Physiology, Yale University, New Haven, Connecticut 06520.; Systems Biology Institute, Yale University, New Haven, Connecticut 06520., Ibba M; Department of Microbiology, The Ohio State University, Columbus, Ohio 43220 ibba.1@osu.edu.
Jazyk: angličtina
Zdroj: The Journal of biological chemistry [J Biol Chem] 2020 Jan 31; Vol. 295 (5), pp. 1402-1410. Date of Electronic Publication: 2019 Dec 20.
DOI: 10.1074/jbc.RA119.011714
Abstrakt: 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/PP i 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-tRNA Ala 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.
(© 2020 Han et al.)
Databáze: MEDLINE
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