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Loss of protein synthesis quality control in host-restricted organisms

Lookup NU author(s): Dr Sergey MelnikovORCiD



This is the authors' accepted manuscript of an article that has been published in its final definitive form by National Academy of Sciences, 2018.

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© 2018 National Academy of Sciences. All rights reserved.Intracellular organisms, such as obligate parasites and endosymbionts, typically possess small genomes due to continuous genome decay caused by an environment with alleviated natural selection. Previously, a few species with highly reduced genomes, including the intracellular pathogens Mycoplasma and Microsporidia, have been shown to carry degenerated editing domains in aminoacyl-tRNA synthetases. These defects in the protein synthesis machinery cause inaccurate translation of the genetic code, resulting in significant statistical errors in protein sequences that are thought to help parasites to escape immune response of a host. In this study we analyzed 10,423 complete bacterial genomes to assess conservation of the editing domains in tRNA synthetases, including LeuRS, IleRS, ValRS, ThrRS, AlaRS, and PheRS. We found that, while the editing domains remain intact in free-living species, they are degenerated in the overwhelming majority of host-restricted bacteria. Our work illustrates that massive genome erosion triggered by an intracellular lifestyle eradicates one of the most fundamental components of a living cell: the system responsible for proofreading of amino acid selection for protein synthesis. This finding suggests that inaccurate translation of the genetic code might be a general phenomenon among intercellular organisms with reduced genomes.

Publication metadata

Author(s): Melnikov SV, van den Elzen A, Stevens DL, Thoreen CC, Soll D

Publication type: Article

Publication status: Published

Journal: Proceedings of the National Academy of Sciences of the United States of America

Year: 2018

Volume: 115

Issue: 49

Pages: E11505-E11512

Print publication date: 04/12/2018

Online publication date: 19/11/2018

Acceptance date: 18/10/2018

Date deposited: 16/07/2020

ISSN (print): 0027-8424

ISSN (electronic): 1091-6490

Publisher: National Academy of Sciences


DOI: 10.1073/pnas.1815992115

PubMed id: 30455292


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