Version 1
: Received: 9 April 2020 / Approved: 12 April 2020 / Online: 12 April 2020 (08:47:26 CEST)
Version 2
: Received: 21 June 2021 / Approved: 23 June 2021 / Online: 23 June 2021 (11:45:40 CEST)
Version 3
: Received: 8 September 2021 / Approved: 8 September 2021 / Online: 8 September 2021 (12:31:24 CEST)
Version 4
: Received: 6 July 2022 / Approved: 7 July 2022 / Online: 7 July 2022 (04:15:26 CEST)
Version 5
: Received: 3 October 2022 / Approved: 11 October 2022 / Online: 11 October 2022 (07:11:27 CEST)
How to cite:
Francis, W. The Eukaryotic Last Common Ancestor Was Bifunctional for Hopanoid and Sterol Production. Preprints2020, 2020040186. https://doi.org/10.20944/preprints202004.0186.v2
Francis, W. The Eukaryotic Last Common Ancestor Was Bifunctional for Hopanoid and Sterol Production. Preprints 2020, 2020040186. https://doi.org/10.20944/preprints202004.0186.v2
Francis, W. The Eukaryotic Last Common Ancestor Was Bifunctional for Hopanoid and Sterol Production. Preprints2020, 2020040186. https://doi.org/10.20944/preprints202004.0186.v2
APA Style
Francis, W. (2021). The Eukaryotic Last Common Ancestor Was Bifunctional for Hopanoid and Sterol Production. Preprints. https://doi.org/10.20944/preprints202004.0186.v2
Chicago/Turabian Style
Francis, W. 2021 "The Eukaryotic Last Common Ancestor Was Bifunctional for Hopanoid and Sterol Production" Preprints. https://doi.org/10.20944/preprints202004.0186.v2
Abstract
Steroid and hopanoid biomarkers can be found in ancient rocks and may give a glimpse of what life was present at that time. Sterols and hopanoids are produced by two related enzymes, though the evolutionary history of this protein family is complicated by losses and horizontal gene transfers, and appears to be widely misinterpretted. Here, I have added sequences from additional key species, and re-analysis of the phylogeny of SHC and OSC indicates a single origin of both enzymes among eukaryotes. This pattern is best explained by vertical inheritance of both enzymes from a bacterial ancestor, followed by widespread loss of SHC, and two subsequent HGT events to ferns and ascomycetes. Thus, the last common ancestor of eukaryotes would have been bifunctional for both sterol and hopanoid production. Later enzymatic innovations allowed diversification of sterols in eukaryotes. Contrary to previous interpretations, the LCA of eukaryotes potentially would have been able to produce hopanoids as a substitute for sterols in anaerobic conditions. Without invoking any other metabolic demand, the LCA of eukaryotes could have been a facultative aerobe, living in unstable conditions with respect to oxygen level.
Biology and Life Sciences, Ecology, Evolution, Behavior and Systematics
Copyright:
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Commenter: Warren Francis
Commenter's Conflict of Interests: Author