TY - JOUR
T1 - A nematode sterol C4α-methyltransferase catalyzes a new methylation reaction responsible for sterol diversity
AU - Zhou, Wenxu
AU - Fisher, Paxtyn M.
AU - Vanderloop, Boden H.
AU - Shen, Yun
AU - Shi, Huazhong
AU - Maldonado, Adrian J.
AU - Leaver, David J.
AU - David Nes, W.
N1 - Funding Information:
This work was supported by National Institutes of Health Grant R21/33 AI119782 (W.D.N.). and a student stipend from the Sul Ross State University Ronald E. McNair Post-Baccalaureate Achievement Program (P217A120047; A.J.M.). The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health. The authors declare that they have no conflicts of interest with the contents of this article. Author’s Choice—Final version open access under the terms of the Creative Commons CC-BY license. Manuscript received 25 August 2019 and in revised form 22 September 2019. Published, JLR Papers in Press, September 23, 2019 DOI https://doi.org/10.1194/jlr.RA119000317
Publisher Copyright:
© 2020 Zhou et al. Published by The American Society for Biochemistry and
PY - 2020
Y1 - 2020
N2 - Primitive sterol evolution plays an important role in fossil record interpretation and offers potential therapeutic avenues for human disease resulting from nematode infections. Recognizing that C4-methyl stenol products [8(14)-lophenol] can be synthesized in bacteria while C4-methyl stanol products (dinosterol) can be synthesized in dinoflagellates and preserved as sterane biomarkers in ancient sedimentary rock is key to eukaryotic sterol evolution. In this regard, nematodes have been proposed to convert dietary cholesterol to 8(14)-lophenol by a secondary metabolism pathway that could involve sterol C4 methylation analogous to the C2 methylation of hopanoids (radicle-type mechanism) or C24 methylation of sterols (carbocation-type mechanism). Here, we characterized dichotomous cholesterol metabolic pathways in Caenorhabditis elegans that generate 3-oxo sterol intermediates in separate paths to lophanol (4-methyl stanol) and 8(14)-lophenol (4-methyl stenol). We uncovered alternate C3-sterol oxidation and Δ7 desaturation steps that regulate sterol flux from which branching metabolite networks arise, while lophanol/8(14)-lophenol formationisshowntobedependentonasterolC4α-methyltransferse (4-SMT) that requires 3-oxo sterol substrates and catalyzes a newly discovered 3-keto-enol tautomerism mechanism linked to S-adenosyl-l-methionine-dependent methylation. Alignment-specific substrate-binding domains similarly conserved in 4-SMT and 24-SMT enzymes, despite minimal amino acid sequence identity, suggests divergence from a common, primordial ancestor in the evolution of methyl sterols. The combination of these results provides evolutionary leads to sterol diversity and points to cryptic C4-methyl steroidogenic pathways of targeted convergence that mediate lineage-specific adaptations.methylation reaction responsible for sterol diversity.
AB - Primitive sterol evolution plays an important role in fossil record interpretation and offers potential therapeutic avenues for human disease resulting from nematode infections. Recognizing that C4-methyl stenol products [8(14)-lophenol] can be synthesized in bacteria while C4-methyl stanol products (dinosterol) can be synthesized in dinoflagellates and preserved as sterane biomarkers in ancient sedimentary rock is key to eukaryotic sterol evolution. In this regard, nematodes have been proposed to convert dietary cholesterol to 8(14)-lophenol by a secondary metabolism pathway that could involve sterol C4 methylation analogous to the C2 methylation of hopanoids (radicle-type mechanism) or C24 methylation of sterols (carbocation-type mechanism). Here, we characterized dichotomous cholesterol metabolic pathways in Caenorhabditis elegans that generate 3-oxo sterol intermediates in separate paths to lophanol (4-methyl stanol) and 8(14)-lophenol (4-methyl stenol). We uncovered alternate C3-sterol oxidation and Δ7 desaturation steps that regulate sterol flux from which branching metabolite networks arise, while lophanol/8(14)-lophenol formationisshowntobedependentonasterolC4α-methyltransferse (4-SMT) that requires 3-oxo sterol substrates and catalyzes a newly discovered 3-keto-enol tautomerism mechanism linked to S-adenosyl-l-methionine-dependent methylation. Alignment-specific substrate-binding domains similarly conserved in 4-SMT and 24-SMT enzymes, despite minimal amino acid sequence identity, suggests divergence from a common, primordial ancestor in the evolution of methyl sterols. The combination of these results provides evolutionary leads to sterol diversity and points to cryptic C4-methyl steroidogenic pathways of targeted convergence that mediate lineage-specific adaptations.methylation reaction responsible for sterol diversity.
KW - 8(14)-lophenol
KW - Biosynthesis
KW - Caenorhabditis elegans
KW - Evolution
UR - http://www.scopus.com/inward/record.url?scp=85078868506&partnerID=8YFLogxK
U2 - 10.1194/jlr.RA119000317
DO - 10.1194/jlr.RA119000317
M3 - Article
C2 - 31548366
AN - SCOPUS:85078868506
VL - 61
SP - 192
EP - 204
JO - Journal of Lipid Research
JF - Journal of Lipid Research
SN - 0022-2275
IS - 2
ER -