Membrane protein mediated bilayer communication in networks of droplet interface bilayers

Abstract

Droplet interface bilayers (DIBs) are model membranes formed between lipid monolayerencased water droplets in oil. Compared to conventional methods, one of the most unique properties of DIBs is that they can be connected together to generate multi-layered 'tissuelike' networks, however introducing communication pathways between these compartments typically relies on water-soluble pores that are unable to gate. Here, we show that network connectivity can instead be achieved using a water-insoluble membrane protein by successfully reconstituting a chemically activatable mutant of the mechanosensitive channel MscL into a network of DIBs. Moreover, we also show how the small molecule activator can diffuse through an open channel and across the neighbouring droplet to activate MscL present in an adjacent bilayer. This demonstration of membrane protein mediated bilayer communication could prove key toward developing the next generation of responsive bilayer networks capable of defining information flow inside a minimal tissue.

Activating mechanosensitive channels embedded in droplet interface bilayers using membrane asymmetry

“…1A and S1 † ) exactly as described in our previous work, applying a −100 mV potential across the bilayer. 56 …”

“…We additionally observed events occurring at S13 $42 pA (0.42 nS, n ¼ 3), which we assign to the sub-conducting state of MscL observed in our previous work. 56 At times, we saw combinations of such states leading to the observation of events $55 pA (Fig. 3A(iv)), which could represent the gating of two separate MscL proteins or a change in the conformational state of a single channel.…”

“…1A and S1 †) exactly as described in our previous work, applying a À100 mV potential across the bilayer. 56 To generate asymmetric DIBs, the rst droplet was formed containing PC : PG : LPC vesicles with increasing LPC concentrations (5, 10 and 15 mol%), whilst a second droplet was formed containing PC:PG vesicles AE MscL (Fig. 3A, B and S9 † for 15, 10 and 5 mol% LPC traces respectively).…”

A lipid-based parallel processor for chemical signals

“…Those devised for drug delivery are designed to release their contents. The release can be passive through biodegradation 2 or targeted through structural degradation coupled to environmental triggers such as pH, ultrasound or other external signals 2–5 . More sophisticated single compartments exhibit cell-like features.…”

“…More sophisticated single compartments exhibit cell-like features. For example, they can employ pore-forming membrane proteins to release contents without structural degradation in response to a trigger 1,5 . They may also receive signals from the environment to activate internal chemical processes such as ATP generation 6,7 , protein expression through transcription and translation 7,8 or glucose metabolism 9 .…”