1.D.90. The Channel-forming Transmembrane Multi-block Amphiphile (CTMA) Family
Mechanical stress is sensed by many membrane proteins, but rarely by synthetic molecules. Nevertheless, synthetic tension-responsive transmembrane multi-block amphiphiles have been shown to form transmembrane channels (Muraoka et al. 2017). In membranes, a single-transmembrane amphiphile responds to both expanding and contracting tensions to weaken and strengthen the stacking of membrane-spanning units, respectively, and ion transport is triggered by an expanding tension to form a supramolecular channel, while little transport is observed under tensionless conditions. In contrast, a three-transmembrane amphiphile showed little spectroscopic response to tensions, likely due to weaker stacking of membrane-spanning units than the single-transmembrane amphiphile. Nevertheless, the three-transmembrane amphiphile shows ion transport by forming a unimolecular channel, even under tensionless conditions, and the ion transporting activity decreased by expanding the tension. The estimated operating force of these synthetic systems was comparable to those of mechano-sensitive proteins (Muraoka et al. 2017).