The minimal chemotactic cell.

The movement of cells and microorganisms in response to chemical gradients, chemotaxis, is fundamental to the evolution of myriad biological processes. In this work, we demonstrate that even the simplest cell-like structures are capable of chemotactic navigation. By encapsulating enzymes within lipid vesicles that incorporate a minimal number of membrane pores, we reveal that a solitary vesicle can actively propel itself toward an enzyme substrate gradient. Specifically, vesicles loaded with either glucose oxidase or urease and embedded with corresponding transmembrane proteins were tracked within a microfluidic device under a controlled substrate gradient. Our findings establish that a system comprising only an encapsulated enzyme and a single transmembrane pore is sufficient to initiate chemotaxis. This proof-of-concept model underscores the minimalistic yet powerful nature of cellular navigation mechanisms, providing a previously unknown perspective on the origins and evolution of chemotactic behavior in biological systems.