The Mechanosensitive Channel of Small Conductance (MscS) Superfamily: Not Just Mechanosensitive Channels Anymore

Abstract

A family of many talents: The mechanosensitive channel of small conductance (MscS) superfamily of ion channels is composed of 15 unique subfamilies. Many of these subfamilies are predicted to be nonmechanosensitive and to have evolved to play critical roles in bacterial signal transduction.

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

“…E. coli MscS is among the smallest members of its eponymous family of proteins, and deletion studies indicate that it contains little nonessential protein sequence (Miller et al, 2003b;Schumann et al, 2004). However, other MscS family members show substantial variation in size and topology, containing anywhere from 3 to 12 TM helices ) and a variety of domains not found in MscS, such as large cytoplasmic loops, N-or C-terminal extensions, extracellular domains, and ion or cyclic nucleotide binding motifs (Li et al, 2002(Li et al, , 2007Haswell et al, 2011;Malcolm and Maurer, 2012;Nakayama et al, 2012;Wilson et al, 2013).…”

United in Diversity: Mechanosensitive Ion Channels in Plants

“…MscS serves as an emergency release valve under conditions of hypoosmotic shock in E. coli (11, 70). Genes predicted to encode homologs of MscS are found throughout bacterial and archaeal genomes; in some protist genomes, including pathogenic protozoa; and in all plant genomes so far examined (6, 43, 61, 62, 78, 101, 102, 127). MscS homologs have not yet been identified in animal genomes.…”

“…Among others, domains associated with cyclic nucleotide, Ca 2+ , or K + binding are appended to the basic MscS topology (78, 117, 127). In addition, plant MSL proteins localize to multiple cellular compartments, providing further evidence that they serve a diverse set of functions within the cell (Figure 2b).…”

“…Although MscS functions as an emergency release valve in E. coli , it has become clear that it and other members of the MscS superfamily serve multiple complex roles in both prokaryotes and eukaryotes (reviewed in 10, 22, 78, 127). Based on the diverse localization, topology, and domain structure observed within the MscS superfamily, we have previously suggested that ( a ) some MSL channels may respond to osmotic stress other than that provided by the extracellular environment, ( b ) some may be regulated by mechanisms other than membrane tension, and ( c ) some might even have functions that are completely separable from their role in mediating ion flux (46).…”

Recent characterizations of MscS and its homologs provide insight into the basis of ion selectivity in mechanosensitive channels

“…We previously demonstrated that EcMscS can be expressed mechanosensitive channel pore through the binding of ions, small molecules or other proteins. 11,14 Several MscS homologs have been characterized by single-channel electrophysiology including MscMJ and MscMJLR from Methanococcus jannaschii, 15 MscK and MscM from E. coli, [16][17][18] TtMscS from Thermoanaerobacter tengcongensis, 19 MscCG from Corynebacterium glutamicum 20 and MSC1, a chloroplasttargeted homolog from the green alga Chlamydomonas reinhardtii. 21 In addition, a family of bacterial cyclic nucleotide gated channels with homology to MscS has been reported.…”