Microbial Eukaryotes that Lack Sterols |
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| Authors: | Kiyotaka Takishita Yoshito Chikaraishi Goro Tanifuji Naohiko Ohkouchi Tetsuo Hashimoto Katsunori Fujikura Andrew J. Roger |
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| Affiliation: | 1. Japan Agency for Marine‐Earth Science and Technology (JAMSTEC), Yokosuka, Kanagawa, Japan;2. Institute of Low Temperature Science, Hokkaido University, Sapporo, Hokkaido, Japan;3. Department of Zoology, National Museum of Nature and Science, Tsukuba, Ibaraki, Japan;4. Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki, Japan;5. Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, NS, Canada |
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| Abstract: | It is widely held that sterols are key cyclic triterpenoid lipids in eukaryotic cell membranes and are synthesized through oxygen‐dependent multienzyme pathways. However, there are known exceptions―ciliated protozoans, such as Tetrahymena, along with diverse low‐oxygen‐adapted eukaryotes produce, instead of sterols, the cyclic triterpenoid lipid tetrahymanol that does not require molecular oxygen for its biosynthesis. Here, we report that a number of anaerobic microbial eukaryotes (protists) utilize neither sterols nor tetrahymanol in their membranes. The lack of detectable sterol‐like compounds in their membranes may provide an opportunity to reconsider the physiological function of sterols and sterol‐like lipids in eukaryotes. |
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| Keywords: | Anaerobic gas chromatography/mass spectrometry oxidosqualene cyclase phylogeny squalene‐tetrahymanol cyclase tetrahymanol |
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