MscS Mechanosensitive Channels


The MscS Family of E. coli K-12 is a paralogous family of 6 genes: mscS, kefA, ybiO, yjeP, mscM(ybdG) and ynaI.
MscS, KefA and MscM(YbdG) have been shown to be mechanosensitive channel proteins. YbiO, YjeP, and YnaI are predicted to be mechanosensitive channel proteins.
Full length MscS is homologous to the C-terminal domains of the other 5 proteins: YjeP, 802-1107; KefA, 814-1120; YnaI, 54-343; YbiO, 443-741; MscM(YbdG), 13-415.

A description of this family can be found at the Transport Classification DataBase TCDB: TC 1.A.23.


EcoFam Multiple Alignment of the MscS Family:
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EcoFam Paralog Tree of the MscS Family:
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The crystal structure of MscS PDB 1MXM was used to drive the multiple alignment and derive trees using the EXPRESSO(3DCoffee) server at the Structural and Genomic Information Laboratory (IGS) of CNRS at the Institute for Structural Biology and Microbiology (IBSM) in Marseille, France. The multiple alignment figure was produced using the ESPript server at the Université de Lyon, France. The unrooted tree diagrams are drawn using the Phylodendron server at Indiana University.
YbdG is an anomalous protein in that three insert regions do not correspond to regions in the other proteins.They are residues Q77-E94 (18 aa = X1), L119-L160 (42 aa = X2), and D270-L318 (49 aa = X3). Regions X1, X2 and X3 are deleted from the YbdG sequence used for the multiple alignment and they have each been replaced by a single "X" to mark the point of deletion. This was done to help preserve the alignment of the homologous regions. Nonetheless, the alignment without YbdG is significantly different and shows some additional conservation. Therefore the five gene alignment is also provided:
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There are three functionally characterized members of this family in E. coli : MscS, KefA, MscL and MscM(YdbG) including intermediate (small)(S), and mini(M) conductance proteins.
MscL encodes a mechanosensitive channel protein of large conductance that is unrelated to the MscS family.

In addition to the MscS-homologous C-terminal domains, proteins KefA, YbiO and YjeP have long N-terminal domains of unknown function.

Pivetti et al. (2003) provide an excellent analysis of all MscS and MscL family members, including a comprehensive MscS family member compilation in Table 2 and an MscS family phylogenetic tree in Figure 8A.

YnaI (mislabeled as YjcR in the text) is noted as Eco4 in both Table 2 and Figure 8A. MscS is referred to by its synonym YggB. MscM(YbdG) is referred to as Eco6.