Membrane morphologies arising from multiconformational protein states.

Dynamic compartmentalization by lipid membranes is a hallmark of living cells. The shapes of membrane surfaces are tightly coupled to their various functions, resulting in the myriad of complex membranal geometries. It has long been established by both theory and experiment that cells actively sculpt the shapes of membranes by utilizing curvature-stabilizing proteins that modulate the effective elastic properties of the membrane. Although it has also been known that many membrane proteins may transition between alternative conformational states, the implications of these conformational changes on membrane shaping are largely undetermined. Using continuum-based physical modeling, we explore how membrane proteins with multiple conformations can collectively shape biological membranes. We show that the conformational flexibility of such proteins may lead to emergent behaviors, such as mechanical bistability of the membrane and collective organization. We introduce a curvature-based shape discretization scheme that allows for efficient representation of membrane geometries and demonstrates that membranes embedded with such proteins can spontaneously adopt nonuniform shapes, driven by spatial patterning of protein conformational states, or by redistribution of the proteins in the membrane plane. Our general mechanism highlights how multistate proteins may collectively orchestrate large-scale morphological changes, providing a fundamental insight into the functional organization of diverse biological membrane systems.