Motor-Driven Assembly of Dynamic, Self-Healing Lipid Nanotube Networks

Abstract

Interconnected and highly reticulated lipid organelles such as the endoplasmic reticulum play important roles in wide range of physiological processes. While these structures provide a matrix for organizing membrane constituents, the lumen represents a continuous nanofluidic network for the transport of proteins and small molecules throughout the cells. Here, we describe a system in which synthetic interconnected, millimeter-scale nanofluidic networks were formed from the cooperative interaction between phospholipid vesicles and motor protein-based transport. In this system, the energy-driven transport of microtubule filaments by kinesin motors provides a pulling force that acts on multilamellar liposomes, connected via biotin-streptavidin bonds, and results in the formation of highly bifurcated networks of lipid nanotubes. Moreover, the processing of microtubules by the motors enables self-healing within this system in which nanotubes are continuously elongating and collapsing while maintaining the overall network morphology. The size/shape of the networks can be further modulated by regulating microtubule surface density, as well as total amount and physical properties of the lipid. Once formed, we characterized the diffusivity of the lipids and the ability of these networks to support materials transport. Attachment of quantum dots to lipids within the networks suggests that the lipids remain highly fluid, and that particle transport closely follows a one-dimensional process when the particle density is low, and a single-file, one-dimensional process when particle density is high. Current work is focused on characterizing the connectivity of multi-vesicle networks and interstitial materials transport as a model system for studying biomolecular transport and communication.Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.