Print Email Facebook Twitter A squalene-hopene cyclase in Schizosaccharomyces japonicus represents a eukaryotic adaptation to sterol-limited anaerobic environments Title A squalene-hopene cyclase in Schizosaccharomyces japonicus represents a eukaryotic adaptation to sterol-limited anaerobic environments Author Bouwknegt, J. (TU Delft BT/Industriele Microbiologie) Wiersma, S.J. (TU Delft BT/Industriele Microbiologie) Ortiz Merino, R.A. (TU Delft BT/Industriele Microbiologie) Doornenbal, E.S.R. (TU Delft Economics of Technology and Innovation) Buitenhuis, Petrik (Student TU Delft) Giera, Martin (Leiden University Medical Center) Müller, Christoph (Ludwig Maximilians University) Pronk, J.T. (TU Delft BT/Biotechnologie) Department BT/Biotechnologie Date 2021 Abstract Biosynthesis of sterols, which are key constituents of canonical eukaryotic membranes, requiresmolecular oxygen. Anaerobic protists and deep-branching anaerobic fungi are the only eukaryotes in which a mechanism for sterol-independent growth has been elucidated. In these organisms, tetrahymanol, formed through oxygen-independent cyclization of squalene by a squalene-tetrahymanol cyclase, acts as a sterol surrogate. This study confirms an early report [C. J. E. A. Bulder, Antonie Van Leeuwenhoek, 37, 353-358 (1971)] that Schizosaccharomyces japonicus is exceptional among yeasts in growing anaerobically on synthetic media lacking sterols and unsaturated fatty acids. Mass spectrometry of lipid fractions of anaerobically grown Sch. japonicus showed the presence of hopanoids, a class of cyclic triterpenoids not previously detected in yeasts, including hop-22(29)-ene, hop- 17(21)-ene, hop-21(22)-ene, and hopan-22-ol. A putative gene in Sch. japonicus showed high similarity to bacterial squalene-hopene cyclase (SHC) genes and in particular to those of Acetobacter species. No orthologs of the putative Sch. japonicus SHC were found in other yeast species. Expression of the Sch. japonicus SHC gene (Sjshc1) in Saccharomyces cerevisiae enabled hopanoid synthesis and stimulated anaerobic growth in sterol-free media, thus indicating that one or more of the hopanoids produced by SjShc1 could at least partially replace sterols. Use of hopanoids as sterol surrogates represents a previously unknown adaptation of eukaryotic cells to anaerobic growth. The fast anaerobic growth of Sch. japonicus in sterol-free media is an interesting trait for developing robust fungal cell factories for application in anaerobic industrial processes. Subject AnaerobicHopanoidsSchizosaccharomycesSterolsYeast To reference this document use: http://resolver.tudelft.nl/uuid:3f6ae34a-6142-48e1-b69c-039b0fd15578 DOI https://doi.org/10.1073/pnas.2105225118 ISSN 0027-8424 Source Proceedings of the National Academy of Sciences of the United States of America, 118 (32) Part of collection Institutional Repository Document type journal article Rights © 2021 J. Bouwknegt, S.J. Wiersma, R.A. Ortiz Merino, E.S.R. Doornenbal, Petrik Buitenhuis, Martin Giera, Christoph Müller, J.T. Pronk Files PDF e2105225118.full.pdf 1.52 MB Close viewer /islandora/object/uuid:3f6ae34a-6142-48e1-b69c-039b0fd15578/datastream/OBJ/view