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Sterol methyltransferases in uncultured bacteria complicate eukaryotic biomarker interpretations.

ABSTRACT: Sterane molecular fossils are broadly interpreted as eukaryotic biomarkers, although diverse bacteria also produce sterols. Steranes with side-chain methylations can act as more specific biomarkers if their sterol precursors are limited to particular eukaryotes and are absent in bacteria. One such sterane, 24-isopropylcholestane, has been attributed to demosponges and potentially represents the earliest evidence for animals on Earth, but enzymes that methylate sterols to give the 24-isopropyl side-chain remain undiscovered. Here, we show that sterol methyltransferases from both sponges and yet-uncultured bacteria function in vitro and identify three methyltransferases from symbiotic bacteria each capable of sequential methylations resulting in the 24-isopropyl sterol side-chain. We demonstrate that bacteria have the genomic capacity to synthesize side-chain alkylated sterols, and that bacterial symbionts may contribute to 24-isopropyl sterol biosynthesis in demosponges. Together, our results suggest bacteria should not be dismissed as potential contributing sources of side-chain alkylated sterane biomarkers in the rock record.

SUBMITTER: Brown MO

PROVIDER: S-EPMC10070321 | biostudies-literature | 2023 Apr

REPOSITORIES: biostudies-literature

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Sterol methyltransferases in uncultured bacteria complicate eukaryotic biomarker interpretations.

Brown Malory O MO Olagunju Babatunde O BO Giner José-Luis JL Welander Paula V PV

Nature communications 20230403 1

Sterane molecular fossils are broadly interpreted as eukaryotic biomarkers, although diverse bacteria also produce sterols. Steranes with side-chain methylations can act as more specific biomarkers if their sterol precursors are limited to particular eukaryotes and are absent in bacteria. One such sterane, 24-isopropylcholestane, has been attributed to demosponges and potentially represents the earliest evidence for animals on Earth, but enzymes that methylate sterols to give the 24-isopropyl si ...[more]

PMID: 37012227

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Dataset Information

Sterol methyltransferases in uncultured bacteria complicate eukaryotic biomarker interpretations.

Publications

Sterol methyltransferases in uncultured bacteria complicate eukaryotic biomarker interpretations.

Similar Datasets

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