1. Structural Biology and Molecular Biophysics
  2. Evolutionary Biology
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Methylation at the C-2 position of hopanoids increases rigidity in native bacterial membranes

  1. Chia-Hung Wu
  2. Maja Bialecka-Fornal
  3. Dianne K Newman  Is a corresponding author
  1. California Institute of Technology, United States
Research Article
  • Cited 16
  • Views 1,365
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Cite this article as: eLife 2015;4:e05663 doi: 10.7554/eLife.05663

Abstract

Sedimentary rocks host a vast reservoir of organic carbon, such as 2-methylhopane biomarkers, whose evolutionary significance we poorly understand. Our ability to interpret this molecular fossil record is constrained by ignorance of the function of their molecular antecedents. To gain insight into the meaning of 2-methylhopanes, we quantified the dominant (des)methylated hopanoid species in the membranes of the model hopanoid-producing bacterium Rhodopseudomonas palustris TIE-1. Fluorescence polarization studies of small unilamellar vesicles revealed that hopanoid 2-methylation specifically renders native bacterial membranes more rigid at concentrations that are relevant in vivo. That hopanoids differentially modify native membrane rigidity as a function of their methylation state indicates that methylation itself promotes fitness under stress. Moreover, knowing the in vivo (2Me)-hopanoid concentration range in different cell membranes, and appreciating that (2Me)-hopanoids' biophysical effects are tuned by the lipid environment, permits the design of more relevant in vitro experiments to study their physiological functions.

Article and author information

Author details

  1. Chia-Hung Wu

    Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, United States
    Competing interests
    The authors declare that no competing interests exist.
  2. Maja Bialecka-Fornal

    Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, United States
    Competing interests
    The authors declare that no competing interests exist.
  3. Dianne K Newman

    Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, United States
    For correspondence
    dkn@caltech.edu
    Competing interests
    The authors declare that no competing interests exist.

Reviewing Editor

  1. Jon Clardy, Harvard Medical School, United States

Publication history

  1. Received: November 18, 2014
  2. Accepted: January 14, 2015
  3. Accepted Manuscript published: January 19, 2015 (version 1)
  4. Version of Record published: February 23, 2015 (version 2)

Copyright

© 2015, Wu 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.

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