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Methylation at the C-2 position of hopanoids increases rigidity in native bacterial membranes

Wu, Chia-Hung and Bialecka-Fornal, Maja and Newman, Dianne K. (2015) Methylation at the C-2 position of hopanoids increases rigidity in native bacterial membranes. eLife, 4 . Art. No. e05663. ISSN 2050-084X. PMCID PMC4337730.

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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.

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Newman, Dianne K.0000-0003-1647-1918
Additional Information:© 2015 The Authors. Copyright Wu et al. This article is distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use and redistribution provided that the original author and source are credited. Received: 18 November 2014; accepted: 14 January 2015; published: 19 January 2015. We thank the members of the Newman lab for critical comments on the manuscript. We thank Dr Nathan Dalleska for help with UPLC-TOF-MS. The UPLC-TOF-MS equipment in the California Institute of Technology’s Environmental Analysis Center was used in the work. We thank Dr Heun Jin Lee and Dr Eva Schmid for vesicle preparation advice. This work was supported by grants from NASA (NNX12AD93G), the National Science Foundation (1224158), and the Howard Hughes Medical Institute (HHMI) to DKN. DKN is an HHMI Investigator.
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Howard Hughes Medical Institute (HHMI)UNSPECIFIED
PubMed Central ID:PMC4337730
Record Number:CaltechAUTHORS:20150303-083043246
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:55448
Deposited By: Jason Perez
Deposited On:04 Mar 2015 00:31
Last Modified:03 Oct 2019 08:05

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