Sensing and Responding to Membrane Tension: The Bacterial MscL Channel as a Model System

Department of Physiology, UT Southwestern Medical Center at Dallas, Dallas, Texas. USA.
Biophysical Journal (Impact Factor: 3.97). 07/2012; 103(2):169-74. DOI: 10.1016/j.bpj.2012.06.021
Source: PubMed

ABSTRACT Mechanosensors are important for many life functions, including the senses of touch, balance, and proprioception; cardiovascular regulation; kidney function; and osmoregulation. Many channels from an assortment of families are now candidates for eukaryotic mechanosensors and proprioception, as well as cardiovascular regulation, kidney function, and osmoregulation. Bacteria also possess two families of mechanosensitive channels, termed MscL and MscS, that function as osmotic emergency release valves. Of the two channels, MscL is the most conserved, most streamlined in structure, and largest in conductance at 3.6 nS with a pore diameter in excess of 30 Å; hence, the structural changes required for gating are exaggerated and perhaps more easily defined. Because of these properties, as well as its tractable nature, MscL represents a excellent model for studying how a channel can sense and respond to biophysical changes of a lipid bilayer. Many of the properties of the MscL channel, such as the sensitivity to amphipaths, a helix that runs along the membrane surface and is connected to the pore via a glycine, a twisting and turning of the transmembrane domains upon gating, and the dynamic changes in membrane interactions, may be common to other candidate mechanosensors. Here we review many of these properties and discuss their structural and functional implications.

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Available from: Irene Iscla, Sep 03, 2014
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    • "Detergent is another important parameter and, for a given construct, the observed oligomeric state can vary with changes in detergent. Moreover, the physiological function of MscL reflects an intimate coupling to the properties of the lipid bilayer (Iscla and Blount, 2012; Laganowsky et al., 2014) and changes in the membrane environment can influence the gating properties of MscL (Moe et al., 2000). A specific interaction between MtMscL and phosphatidylinositol is crucial for the mechanosensitivity of this channel (Zhong and Blount, 2013). "
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