Lipid Imbalance Generates Golgi Whorls that Sequester Small GTPases

Abstract

Small GTPases are generally viewed as organizers of organelle identity, with different families recruited to specific membranes by compartment-selective targeting mechanisms. Here, we identify a membrane state that reverses this relationship. Excessive peptide S-palmitoylation at Golgi generates multilamellar, filipin-poor whorls that recruit ARF, Rab, and Rho family GTPases normally associated with distinct cellular compartments. The whorls simultaneously excluded Golgi transmembrane residents, coat proteins, ER proteins, a GPI-anchored protein, and other palmitoylated proteins, demonstrating that they were selective membrane compartments rather than nonspecific protein aggregates. Preventing myristoylation of ARF6 or geranylgeranylation of Rab11a strongly reduced recruitment, whereas prenylation alone was insufficient, indicating recognition of a composite membrane-targeting code. Lowering cellular cholesterol promoted whorl formation, whereas cholesterol supplementation suppressed it. Chemically distinct lipid perturbations generated GTPase-positive Golgi whorls, suggesting convergence on a shared membrane-remodeling state. As whorls accumulated, endocytic recycling and anterograde trafficking declined, survival signaling decreased, and viability became poorly reversible. These findings show that lipid imbalance can redirect small GTPases across normal organelle boundaries, converting Golgi-derived membranes into selective sinks for trafficking regulators.