Chemically defined lipid diets reveal the versatility of lipidome remodeling in genomically minimal cells

Safronova, N.; Junghans, L.; Oertel, J.; Fahmy, K.; Sáenz, J. P. (2024) bioRxiv preprint. DOI: 10.1101/2024.10.04.616688

Summary

To experimentally manipulate lipidome complexity in living cells, we developed a chemically defined approach to deliver lipid “diets” to [[mycoplasma-mycoides|Mycoplasma mycoides]] and JCVI-Syn3B by complexing lipids with cyclodextrins. This produced cellular lipidomes ranging from as few as 7 to nearly 30 species. We showed that lipidome composition dictates membrane adaptation to temperature change, that lipidome diversity enhances robustness to hypoosmotic shock, and that impaired acyl chain remodeling in the minimal cell is associated with impaired temperature adaptation. As a proof of principle, we demonstrated that cells with tuneable lipidomes can serve as chassis for screening membrane-active antimicrobial peptides.

Key Findings

• Cyclodextrin-mediated lipid delivery enables chemically defined lipid diets with precise control over the species provided to cells.
• Lipidome diversity (number of species) correlates with cellular robustness to hypoosmotic shock — more diverse lipidomes produce more robust cells.
• Lipidome composition dictates the cell’s capacity for membrane adaptation to temperature change: diets that support acyl chain remodeling enable homeoviscous adaptation; diets that restrict remodeling impair it.
• JCVI-Syn3B has impaired acyl chain remodeling capacity compared to M. mycoides, consistent with reduced genomic complexity.
• Tuneable lipidome cells can be used as antimicrobial peptide screening platforms — a practical application of the minimal membrane system.

Methods

• Cyclodextrin-lipid complexes: methyl-β-cyclodextrin used to solubilize and deliver defined lipid species to cells.
• Shotgun lipidomics: to verify resulting cellular lipidome compositions.
• Osmotic shock assays: propidium iodide-based lysis quantification under hypoosmotic stress.
• Temperature shift experiments: lipidome remodeling monitored after temperature changes.

Significance

This preprint introduced a powerful experimental tool — cyclodextrin-based lipid diets — that makes it possible to titrate lipidome complexity in living cells. The finding that lipidome diversity enhances robustness provides direct evidence that the complexity of natural lipidomes serves a functional purpose beyond any single lipid’s role.