Hopanoid enrichment in a detergent resistant membrane fraction of Crocosphaera watsonii: Implications for bacterial lipid raft formation

Hopanoids are bacterial membrane lipids with close structural and evolutionary ties to sterols. Extraction of hopanoid containing membranes of Crocosphaera watsonii in a non-ionic detergent demonstrates that a hopanoid identified as bacteriohopanetetrol cyclitol ether (BHT-CE) is enriched in a detergent resistant membrane (DRM) fraction. Detergent resistance indicates that hopanoids, like sterols in eukaryotes, are likely associated with putative lipid rafts in bacterial membranes. These results are consistent with previous work suggesting analogous roles of hopanoids and sterols and may imply that hopanoids are essential to the physiology of putative lipid rafts in hopanoid producing bacteria.