Vegetative insecticidal proteins (Vip3s) are a family of insecticidal proteins typically expressed by Bacillus thuringiensis (Bt). Bt and its various families of proteins, including Vip3s, have successfully been deployed as biopesticides for many decades, providing targeted activity against agricultural pests. Despite a long history of safe use in the control of lepidopteran pests, the exact mechanism behind Vip3 function is poorly understood.
Novel biophysical methods have been used to determine the ability of Vip3s to form pores in artificial membranes via Droplet Hydrogel-Supported Bilayers (DHBs) and to elucidate details about the movement of ions through these pores using Droplet Interface Bilayers (DIBs). DHB experiments have demonstrated Vip3-facilitated calcium ion efflux across a bilayer, and DIB experiments have shown Vip3s have a bi-directional pore with potential preference for potassium translocation – details not previously known about these proteins. Structural modelling is being employed to develop our understanding of pore structure, supplementing previous experimental evidence.