BPS2026 – A tunable synthetic tool to sequester organelles via biomolecular condensates

Eukaryotic cells rely on organelles to coordinate essential biochemical processes. Dysregulation of organelle dynamics is implicated in numerous diseases. However, the mechanisms by which cells monitor and regulate organelle abundance remain poorly understood. Traditional approaches are limited: gene knockouts are irreversible and compromise cell fitness, while optogenetic tools are often unstable for dynamic studies. Here, we developed a tunable synthetic system that uses biomolecular condensates to modulate interactions between organelles and the cytoplasm. This system employs PopTag fused to organelle-specific membrane anchors, allowing condensates to form on the organelle surface and physically sequester it from its surroundings. Using Saccharomyces cerevisiae as a model, we demonstrate that PopTag condensates colocalize with mitochondria and peroxisomes. Increasing PopTag expression on the mitochondrial membrane progressively impairs growth, indicating an inverse relationship between condensate formation and cell growth. Transcriptomic profiling reveals widespread gene expression changes compared to controls lacking PopTag or the membrane anchor. Genes encoding complexes in oxidative phosphorylation and enzymes in the tricarboxylic acid (TCA) cycle are broadly downregulated. These findings suggest that the coordination between gene expression and organelle function is demand-driven: cells appear to limit supply of organelle components in the absence of organelle function. Ongoing work investigates the specific pathways involved and how cells sense and respond to organelle sequestration. With further development, this system could serve as a tool to study organelle homeostasis and provide a framework for examining how changes in intracellular organization impact cell physiology and disease.