Unifying Principles of Membrane Adaptation to Pressure-Temperature Niches in the Ocean

Cell membranes are highly sensitive to changes in pressure, temperature, and aqueous chemistry. This drives pronounced biochemical adaptation among marine life to protect membrane integrity and function under diverse conditions. For fifty years, scientists have recognized that organisms adjust the fatty (lipid) building blocks of their membranes to maintain optimal fluidity – a process called homeoviscosity. However, recent studies of comb jellies (ctenophores) from surface waters to 4 km depth have revealed a second, distinct mode of membrane adaptation: homeocurvature. This process regulates the effective shape of lipid molecules in response to hydrostatic pressure, maintaining mechanical properties essential for membrane remodeling and embedded protein function. Pressure perturbs lipid shape more strongly than temperature does, making homeocurvature especially important for deep-sea organisms and oceanic ecosystems. In addition to evidence for homeocurvature derived from ctenophores and engineered bacteria, I will share ongoing work assessing the generality of homeocurvature and its interaction with homeoviscosity, which can involve evolutionary trade-offs. Shape-based lipid homeostasis is evident in yeast, marine bacteria, deep-sea fishes and diving mammals, suggesting widespread relevance across marine ecological niches. As the abiotic factors defining these niches shift at unprecedented rates, it is increasingly urgent that we understand the unifying physical principles of membrane adaptation. Elucidating the underlying biochemistry and genetics across taxa will help predict adaptive trajectories along the arc of global change.