Modulation of Membrane Transport via Lysenin Channels Controlled by Electrochemical Gradients

Document Type

Student Presentation

Presentation Date



College of Arts and Sciences



Faculty Sponsor

Daniel Fologea


Lysenin, a pore forming toxin extracted from the red earthworm E. fetida, self assembles as a large conductance pore in artificial and natural membranes containing sphingomyelin. Unlike many other toxins, the inserted channels are highly regulated by voltage, i.e. open and close in response to external voltage stimuli. This exquisite feature provides opportunities to control the transport of ions and molecules across artificial and natural cell membranes via diffusional transmembrane voltages produced with selective transporters. Additionally, lysenin channels present an inherent ionic selectivity, which may be further used to elicit bias potentials sufficient to induce conformational changes of the channel and conductance control. Our work shows that the permeability of an artificial lipid membrane containing lysenin channels may be easily modulated by adjusting the transmembrane gradient of the ionic concentration and in the absence of any other selective transporter. A more complete channel closure was observed upon addition of valinomycin, a highly selective K+ transporter, which produced a much larger diffusional potential and completely obliterated the membrane permeability function.

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