Membrane stiffness is one of the key determinants of E coli MscS channel echanosensitivity

Publication date: Available online 22 January 2020Source: Biochimica et Biophysica Acta (BBA) - BiomembranesAuthor(s): Feng Xue, Charles D. Cox, Navid Bavi, Paul R. Rohde, Yoshitaka Nakayama, Boris MartinacAbstractMechanosensitive (MS) channels have an intimate relationship with membrane lipids that underlie their mechanosensitivity. Membrane lipids may influence channel activity by directly interacting with MS channels or by influencing the global properties of the membrane such as elastic area expansion modulus or bending rigidity. Previous work has implicated membrane stiffness as a potential determinant of the mechanosensitivity of E. coli (Ec)MscS. Here we systematically tested this hypothesis using patch fluorometry of azolectin liposomes doped with lipids of increasing elastic area expansion modulus. Increasing dioleoylphosphatidylethanolamine (DOPE) content of azolectin liposomes made it more difficult to activate EcMscS by membrane tension (i.e. increased gating threshold). This effect was exacerbated by stiffer forms of phosphatidylethanolamine such as the branched chain lipid diphytanoylphosphoethanolamine (DPhPE) or the fully saturated lipid distearoyl-sn-glycero-3-phosphoethanolamine (DSPE). Furthermore, a comparison of the branched chain lipid diphytanoylphosphocholine (DPhPC) to the stiffer DPhPE indicated again that it was harder to activate EcMscS in the presence of the stiffer DPhPE. We show that these effects are not due to changes in membrane bending rigid...
Source: Biochimica et Biophysica Acta (BBA) Biomembranes - Category: Biochemistry Source Type: research