Why the study?
While myosin adaptors for most organelles are known in yeast, the coupling of myosin to lipid droplets remained enigmatic.
The study identifies Ldm1 and Ldo16 as the essential molecular machinery mediating actin-dependent lipid droplet motility in yeast.
Does not inform clinical lipid management; leaves open conservation of this machinery in mammalian cells.
Organelle motility enables strategic cellular reorganizations. In yeast, this process depends on the actin cytoskeleton, type V myosin motor proteins, and organelle-specific myosin adaptor proteins. While the myosin adaptors for most organelles are known, the coupling of myosin to lipid droplets (LDs), the cellular lipid storage organelles, remained enigmatic. Using genome-wide screening, we identified Ldm1 (lipid droplet motility 1/Yer085c) as a myosin adaptor. Ldm1 binds to the globular tail domain of the myosin Myo2 and to the LD surface protein Ldo16 to enable actin-dependent LD motility. Ldo16 has additional roles in LD contact sites to the vacuole and the endoplasmic reticulum, suggesting a coordination of LD motility and organelle tethering. Ldm1 has a second role in mitochondrial transport, and elevated Ldm1 levels rescue defects of the mitochondrial Myo2-adaptors Mmr1/Ypt11. Our work identifies the molecular machinery for LD motility and contributes to a comprehensive understanding of acto-myosin-based cellular reorganization.
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Zhao et al. (2025) studied this question.
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