Assessment of potential stimuli for mechano-dependent gating of MscL: Effects of pressure, tension, and lipid headgroups

Paul Moe, Paul Blount

Research output: Contribution to journalArticle

127 Citations (Scopus)

Abstract

MscL is a mechanosensitive channel of large conductance that serves as an "emergency relief valve", protecting bacteria from acute hypoosmotic stress. Although it is well-accepted that the MscL protein and an adequate membrane matrix are necessary and sufficient for the function of this channel, the exact role of the membrane has yet to be elucidated. Here, we address the role of the membrane matrix through in vitro reconstitution of the MscL protein in defined lipid bilayers. We have applied Laplace's law to visualized membrane patches where we can measure patch curvature as described in previous studies. Here, by comparing patches with different curvatures, we demonstrate that the MscL channel senses tension within the membrane and that the pressure across it plays no detectable role as a stimulus. In addition, gating only occurs when the smallest radius of curvature is nearly achieved, suggesting that the lateral tension rather than membrane curvature is the important biophysical parameter. Finally, we have examined the contribution of specific headgroups by measuring their effect on the membrane tension required to gate the channel. We have found that the addition of neither anionic nor endogenous lipids to a non-native membrane effected a leftward shift in the activation curve. In fact, the major endogenous lipid of the Escherichia coli membrane, phosphatidylethanolamine, led to a channel activity at a higher tension threshold, suggesting that this lipid effects altered activity through changes in the biophysical properties of the membrane, rather than through an MscL-specific interaction.

Original languageEnglish (US)
Pages (from-to)12239-12244
Number of pages6
JournalBiochemistry
Volume44
Issue number36
DOIs
StatePublished - Sep 13 2005

Fingerprint

Membranes
Lipids
Pressure
Pressure relief valves
Lipid bilayers
Lipid Bilayers
Escherichia coli
Bacteria
Membrane Proteins
Emergencies
Chemical activation
Proteins

ASJC Scopus subject areas

  • Biochemistry

Cite this

Assessment of potential stimuli for mechano-dependent gating of MscL : Effects of pressure, tension, and lipid headgroups. / Moe, Paul; Blount, Paul.

In: Biochemistry, Vol. 44, No. 36, 13.09.2005, p. 12239-12244.

Research output: Contribution to journalArticle

@article{de1ef20b7f324255b61b0284922476e2,
title = "Assessment of potential stimuli for mechano-dependent gating of MscL: Effects of pressure, tension, and lipid headgroups",
abstract = "MscL is a mechanosensitive channel of large conductance that serves as an {"}emergency relief valve{"}, protecting bacteria from acute hypoosmotic stress. Although it is well-accepted that the MscL protein and an adequate membrane matrix are necessary and sufficient for the function of this channel, the exact role of the membrane has yet to be elucidated. Here, we address the role of the membrane matrix through in vitro reconstitution of the MscL protein in defined lipid bilayers. We have applied Laplace's law to visualized membrane patches where we can measure patch curvature as described in previous studies. Here, by comparing patches with different curvatures, we demonstrate that the MscL channel senses tension within the membrane and that the pressure across it plays no detectable role as a stimulus. In addition, gating only occurs when the smallest radius of curvature is nearly achieved, suggesting that the lateral tension rather than membrane curvature is the important biophysical parameter. Finally, we have examined the contribution of specific headgroups by measuring their effect on the membrane tension required to gate the channel. We have found that the addition of neither anionic nor endogenous lipids to a non-native membrane effected a leftward shift in the activation curve. In fact, the major endogenous lipid of the Escherichia coli membrane, phosphatidylethanolamine, led to a channel activity at a higher tension threshold, suggesting that this lipid effects altered activity through changes in the biophysical properties of the membrane, rather than through an MscL-specific interaction.",
author = "Paul Moe and Paul Blount",
year = "2005",
month = "9",
day = "13",
doi = "10.1021/bi0509649",
language = "English (US)",
volume = "44",
pages = "12239--12244",
journal = "Biochemistry",
issn = "0006-2960",
publisher = "American Chemical Society",
number = "36",

}

TY - JOUR

T1 - Assessment of potential stimuli for mechano-dependent gating of MscL

T2 - Effects of pressure, tension, and lipid headgroups

AU - Moe, Paul

AU - Blount, Paul

PY - 2005/9/13

Y1 - 2005/9/13

N2 - MscL is a mechanosensitive channel of large conductance that serves as an "emergency relief valve", protecting bacteria from acute hypoosmotic stress. Although it is well-accepted that the MscL protein and an adequate membrane matrix are necessary and sufficient for the function of this channel, the exact role of the membrane has yet to be elucidated. Here, we address the role of the membrane matrix through in vitro reconstitution of the MscL protein in defined lipid bilayers. We have applied Laplace's law to visualized membrane patches where we can measure patch curvature as described in previous studies. Here, by comparing patches with different curvatures, we demonstrate that the MscL channel senses tension within the membrane and that the pressure across it plays no detectable role as a stimulus. In addition, gating only occurs when the smallest radius of curvature is nearly achieved, suggesting that the lateral tension rather than membrane curvature is the important biophysical parameter. Finally, we have examined the contribution of specific headgroups by measuring their effect on the membrane tension required to gate the channel. We have found that the addition of neither anionic nor endogenous lipids to a non-native membrane effected a leftward shift in the activation curve. In fact, the major endogenous lipid of the Escherichia coli membrane, phosphatidylethanolamine, led to a channel activity at a higher tension threshold, suggesting that this lipid effects altered activity through changes in the biophysical properties of the membrane, rather than through an MscL-specific interaction.

AB - MscL is a mechanosensitive channel of large conductance that serves as an "emergency relief valve", protecting bacteria from acute hypoosmotic stress. Although it is well-accepted that the MscL protein and an adequate membrane matrix are necessary and sufficient for the function of this channel, the exact role of the membrane has yet to be elucidated. Here, we address the role of the membrane matrix through in vitro reconstitution of the MscL protein in defined lipid bilayers. We have applied Laplace's law to visualized membrane patches where we can measure patch curvature as described in previous studies. Here, by comparing patches with different curvatures, we demonstrate that the MscL channel senses tension within the membrane and that the pressure across it plays no detectable role as a stimulus. In addition, gating only occurs when the smallest radius of curvature is nearly achieved, suggesting that the lateral tension rather than membrane curvature is the important biophysical parameter. Finally, we have examined the contribution of specific headgroups by measuring their effect on the membrane tension required to gate the channel. We have found that the addition of neither anionic nor endogenous lipids to a non-native membrane effected a leftward shift in the activation curve. In fact, the major endogenous lipid of the Escherichia coli membrane, phosphatidylethanolamine, led to a channel activity at a higher tension threshold, suggesting that this lipid effects altered activity through changes in the biophysical properties of the membrane, rather than through an MscL-specific interaction.

UR - http://www.scopus.com/inward/record.url?scp=24644491716&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=24644491716&partnerID=8YFLogxK

U2 - 10.1021/bi0509649

DO - 10.1021/bi0509649

M3 - Article

C2 - 16142922

AN - SCOPUS:24644491716

VL - 44

SP - 12239

EP - 12244

JO - Biochemistry

JF - Biochemistry

SN - 0006-2960

IS - 36

ER -