Bacterial Mechanosensitive Channels: Models for Studying Mechanosensory Transduction

Abstract

Significance: Sensations of touch and hearing are manifestations of mechanical contact and air pressure acting on touch receptors and hair cells of the inner ear, respectively. In bacteria, osmotic pressure exerts a significant mechanical force on their cellular membrane. Bacteria have evolved mechanosensitive (MS) channels to cope with excessive turgor pressure resulting from a hypo-osmotic shock. MS channel opening allows the expulsion of osmolytes and water, thereby restoring normal cellular turgor and preventing cell lysis. Recent Advances: As biological force-sensing systems, MS channels have been identified as the best examples of membrane proteins coupling molecular dynamics to cellular mechanics. The bacterial MS channel of large conductance (MscL) and MS channel of small conductance (MscS) have been subjected to extensive biophysical, biochemical, genetic, and structural analyses. These studies have established MscL and MscS as model systems for mechanosensory transduction. Critical Issues: In recent years, MS ion channels in mammalian cells have moved into focus of mechanotransduction research, accompanied by an increased awareness of the role they may play in the pathophysiology of diseases, including cardiac hypertrophy, muscular dystrophy, or Xerocytosis. Future Directions: A recent exciting development includes the molecular identification of Piezo proteins, which function as nonselective cation channels in mechanosensory transduction associated with senses of touch and pain. Since research on Piezo channels is very young, applying lessons learned from studies of bacterial MS channels to establishing the mechanism by which the Piezo channels are mechanically activated remains one of the future challenges toward a better understanding of the role that MS channels play in mechanobiology. Antioxid. Redox Signal. 00, 000-000.

Transcriptomic analysis reveals how a lack of potassium ions increases Sulfolobus acidocaldarius sensitivity to pH changes

“…A small-conductance mechano-sensitive channel (Saci_1914) had a log 2 -FC increase of 7.8 in the presence of full salt. Small-conductance mechano-sensitive channels open and close in response to stretching of the membrane, protecting the cell against osmotic shock (Martinac et al, 2014), and their role in archaea is well established (Kloda & Martinac, 2002).…”

Piezo1 Channels Are Inherently Mechanosensitive

“…Both MscS and MscL respond to extracellular osmotic challenges to prevent cell lysis (Booth, 2014; Martinac et al, 2014). In contrast the physiological role of TRAAK in mechanotransduction is not completely understood, but it is widely expressed in neurons and is involved in mechanical and thermal nociception in mice (Noël et al, 2009).…”

Arabidopsis MSL10 Has a Regulated Cell Death Signaling Activity That Is Separable from Its Mechanosensitive Ion Channel Activity

“…Homologs of MscS are found in nearly all bacterial species (Pivetti et al, 2003;Lai et al, 2013;Martinac et al, 2013), protozoa (Prole and Taylor, 2013), archaea (Palmieri et al, 2009), some fungi (Nakayama et al, 2012), and all plant genomes so far analyzed (Wilson et al, 2013) but have not been identified in animals. The region of sequence similarity between MscS and other members of the MscS superfamily is restricted to a relatively small portion of the protein that includes the pore-lining helix of MscS and ;100 amino acids of the upper cytoplasmic domain (Kloda and Martinac, 2002;Pivetti et al, 2003;Balleza and Gómez-Lagunas, 2009;Haswell et al, 2011).…”