Patch clamp characterization of the effect of cardiolipin on MscS of E. coli
Author(s)
Ridone, Pietro
Nakayama, Yoshitaka
Martinac, Boris
Battle, Andrew
Griffith University Author(s)
Year published
2015
Metadata
Show full item recordAbstract
The bacterial mechanosensitive channels MscS and MscL are gated by an increase in membrane tension when the bacterium experiences hypoosmotic shock. It has been well established that membrane lipids modulate the mechanosensitivity and gating behavior of these channels. The focus of this study is a negatively charged phospholipid, cardiolipin, which has been shown to localize at curved regions of the bacterial cell, including the poles and the septum, and to have a strong preference for binding to membrane proteins. Here we characterize the effect of cardiolipin on MscS, the mechanosensitive channel of small conductance, using ...
View more >The bacterial mechanosensitive channels MscS and MscL are gated by an increase in membrane tension when the bacterium experiences hypoosmotic shock. It has been well established that membrane lipids modulate the mechanosensitivity and gating behavior of these channels. The focus of this study is a negatively charged phospholipid, cardiolipin, which has been shown to localize at curved regions of the bacterial cell, including the poles and the septum, and to have a strong preference for binding to membrane proteins. Here we characterize the effect of cardiolipin on MscS, the mechanosensitive channel of small conductance, using patch-clamp electrophysiology. We compare the gating kinetics and mechanosensitivity of the channel in both azolectin and mixtures of pure lipids DOPE/DOPC liposomes with and without cardiolipin. In azolectin liposomes, the addition of 10 % cardiolipin abolishes hysteresis of MscS, but MscL remains largely unaffected, indicating that cardiolipin may stabilize the closed state of MscS. On the other hand, mixtures of DOPE/DOPC abolish the hysteresis gating of MscS even in the absence of cardiolipin, and the addition of cardiolipin increases the opening and closing thresholds of both MscS and MscL. In addition, we show that MscS gates more frequently when cardiolipin is present in both the azolectin and pure lipid systems; this dose-dependent effect ultimately destabilizes the open state of MscS and we consider the functional implications of this cardiolipin effect in the bacterial osmotic response. Our results show that cardiolipin modulates the mechanosensitivity and gating characteristics of MscS, indicating its important role in the physiology of bacterial cells.
View less >
View more >The bacterial mechanosensitive channels MscS and MscL are gated by an increase in membrane tension when the bacterium experiences hypoosmotic shock. It has been well established that membrane lipids modulate the mechanosensitivity and gating behavior of these channels. The focus of this study is a negatively charged phospholipid, cardiolipin, which has been shown to localize at curved regions of the bacterial cell, including the poles and the septum, and to have a strong preference for binding to membrane proteins. Here we characterize the effect of cardiolipin on MscS, the mechanosensitive channel of small conductance, using patch-clamp electrophysiology. We compare the gating kinetics and mechanosensitivity of the channel in both azolectin and mixtures of pure lipids DOPE/DOPC liposomes with and without cardiolipin. In azolectin liposomes, the addition of 10 % cardiolipin abolishes hysteresis of MscS, but MscL remains largely unaffected, indicating that cardiolipin may stabilize the closed state of MscS. On the other hand, mixtures of DOPE/DOPC abolish the hysteresis gating of MscS even in the absence of cardiolipin, and the addition of cardiolipin increases the opening and closing thresholds of both MscS and MscL. In addition, we show that MscS gates more frequently when cardiolipin is present in both the azolectin and pure lipid systems; this dose-dependent effect ultimately destabilizes the open state of MscS and we consider the functional implications of this cardiolipin effect in the bacterial osmotic response. Our results show that cardiolipin modulates the mechanosensitivity and gating characteristics of MscS, indicating its important role in the physiology of bacterial cells.
View less >
Journal Title
European Biophysics Journal
Volume
44
Issue
7
Subject
Biochemistry and Cell Biology not elsewhere classified
Atomic, Molecular, Nuclear, Particle and Plasma Physics
Other Physical Sciences
Biochemistry and Cell Biology