A bacterial riboswitch class for the thiamin precursor HMP-PP employs a terminator-embedded aptamer

Abstract

We recently implemented a bioinformatics pipeline that can uncover novel, but rare, riboswitch candidates as well as other noncoding RNA structures in bacteria. A prominent candidate revealed by our initial search efforts was called the 'thiS motif' because of its frequent association with a gene coding for the ThiS protein, which delivers sulfur to form the thiazole moiety of the thiamin precursor HET-P. In the current report, we describe biochemical and genetic data demonstrating that thiS motif RNAs function as sensors of the thiamin precursor HMP-PP, which is fused with HET-P ultimately to form the final active coenzyme thiamin pyrophosphate (TPP). HMP-PP riboswitches exhibit a distinctive architecture wherein an unusually small ligand-sensing aptamer is almost entirely embedded within an otherwise classic intrinsic transcription terminator stem. This arrangement yields remarkably compact genetic switches that bacteria use to tune the levels of thiamin precursors during the biosynthesis of this universally distributed coenzyme.

Data availability

All data generated or analyzed during this study are included in the manuscript and supporting files.

Article and author information

Author details

  1. Ruben M Atilho

    Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, United States
    Competing interests
    The authors declare that no competing interests exist.
  2. Gayan Mirihana Arachchilage

    Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, United States
    Competing interests
    The authors declare that no competing interests exist.
  3. Etienne B Greenlee

    Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, United States
    Competing interests
    The authors declare that no competing interests exist.
  4. Kirsten M Knecht

    Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, United States
    Competing interests
    The authors declare that no competing interests exist.
  5. Ronald R Breaker

    Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, United States
    For correspondence
    ronald.breaker@yale.edu
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-2165-536X

Funding

National Institutes of Health (P01 GM022778)

  • Ronald R Breaker

National Science Foundation (Graduate Student Fellowship)

  • Ruben M Atilho

Howard Hughes Medical Institute (Investigator Funding)

  • Ronald R Breaker

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.

Reviewing Editor

  1. Ailong Ke, Cornell University

Publication history

  1. Received: January 15, 2019
  2. Accepted: April 4, 2019
  3. Accepted Manuscript published: April 5, 2019 (version 1)
  4. Version of Record published: April 23, 2019 (version 2)

Copyright

© 2019, Atilho et al.

This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.

Metrics

  • 2,153
    Page views
  • 356
    Downloads
  • 24
    Citations

Article citation count generated by polling the highest count across the following sources: Crossref, PubMed Central, Scopus.

Download links

A two-part list of links to download the article, or parts of the article, in various formats.

Downloads (link to download the article as PDF)

Open citations (links to open the citations from this article in various online reference manager services)

Cite this article (links to download the citations from this article in formats compatible with various reference manager tools)

  1. Ruben M Atilho
  2. Gayan Mirihana Arachchilage
  3. Etienne B Greenlee
  4. Kirsten M Knecht
  5. Ronald R Breaker
(2019)
A bacterial riboswitch class for the thiamin precursor HMP-PP employs a terminator-embedded aptamer
eLife 8:e45210.
https://doi.org/10.7554/eLife.45210

Further reading

    1. Biochemistry and Chemical Biology
    2. Cancer Biology
    Madeleine L Hart, Evan Quon ... Lucas B Sullivan
    Research Article Updated

    The oxidative tricarboxylic acid (TCA) cycle is a central mitochondrial pathway integrating catabolic conversions of NAD +to NADH and anabolic production of aspartate, a key amino acid for cell proliferation. Several TCA cycle components are implicated in tumorigenesis, including loss-of-function mutations in subunits of succinate dehydrogenase (SDH), also known as complex II of the electron transport chain (ETC), but mechanistic understanding of how proliferating cells tolerate the metabolic defects of SDH loss is still lacking. Here, we identify that SDH supports human cell proliferation through aspartate synthesis but, unlike other ETC impairments, the effects of SDH inhibition are not ameliorated by electron acceptor supplementation. Interestingly, we find aspartate production and cell proliferation are restored to SDH-impaired cells by concomitant inhibition of ETC complex I (CI). We determine that the benefits of CI inhibition in this context depend on decreasing mitochondrial NAD+/NADH, which drives SDH-independent aspartate production through pyruvate carboxylation and reductive carboxylation of glutamine. We also find that genetic loss or restoration of SDH selects for cells with concordant CI activity, establishing distinct modalities of mitochondrial metabolism for maintaining aspartate synthesis. These data therefore identify a metabolically beneficial mechanism for CI loss in proliferating cells and reveal how compartmentalized redox changes can impact cellular fitness.

    1. Biochemistry and Chemical Biology
    2. Structural Biology and Molecular Biophysics
    Sean M Braet, Theresa SC Buckley ... Ganesh Srinivasan Anand
    Research Article

    SARS-CoV-2 emergent variants are characterized by increased viral fitness and each shows multiple mutations predominantly localized to the spike (S) protein. Here, amide hydrogen/deuterium exchange mass spectrometry has been applied to track changes in S dynamics from multiple SARS-CoV-2 variants. Our results highlight large differences across variants at two loci with impacts on S dynamics and stability. A significant enhancement in stabilization first occurred with the emergence of D614G S followed by smaller, progressive stabilization in subsequent variants. Stabilization preceded altered dynamics in the N-terminal domain, wherein Omicron BA.1 S showed the largest magnitude increases relative to other preceding variants. Changes in stabilization and dynamics resulting from S mutations detail the evolutionary trajectory of S in emerging variants. These carry major implications for SARS-CoV-2 viral fitness and offer new insights into variant-specific therapeutic development.