An elusive electron shuttle from a facultative anaerobe
- Harvard Medical School, United States
- Lawrence Berkeley National Laboratory, University of California, Berkeley, United States
Abstract
Some anaerobic bacteria use insoluble minerals as terminal electron acceptors and discovering the ways in which electrons move through the membrane barrier to the exterior acceptor forms an active field of research with implications for both bacterial physiology and bioenergy. A previous study suggested that Shewanella oneidensis MR-1 utilizes a small, polar, redox active molecule that serves as an electron shuttle between the bacteria and insoluble acceptors, but the shuttle itself has never been identified. Through isolation and synthesis, we identify it as ACNQ (2-amino-3-carboxy-1,4-naphthoquinone), a soluble analog of menaquinone. ACNQ is derived from DHNA (1,4-dihydroxy-2-naphthoic acid) in a non-enzymatic process that frustrated genetic approaches to identify the shuttle. Both ACNQ and DHNA restore reduction of AQDS under anaerobic growth in menaquinone-deficient mutants. Bioelectrochemistry analyses reveal that ACNQ (-0.32 VAg/AgCl) contributes to the extracellular electron transfer (EET) as an electron shuttle, without altering menaquinone generation or EET related cytochrome c expression.
Data availability
All data generated or analyzed during this study are included in the manuscript and supporting files.
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Author details
Funding
National Institute of General Medical Sciences (GM086258)
- Jon Clardy
National Center for Complementary and Integrative Health (AT980074)
- Jon Clardy
U.S. Department of Energy (DE-AC02-05CH11231)
- Caroline M Ajo-Franklin
National Institute of General Medical Sciences (5F32GM103010)
- Elissa Hobert
China Scholarship Council (201606090098)
- Lin Su
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Copyright
© 2019, Mevers 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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An elusive electron shuttle from a facultative anaerobe
eLife 8:e48054.
https://doi.org/10.7554/eLife.48054
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