title: Patch-clamp characterization of the MscS-like mechanosensitive channel from Silicibacter pomeroyi.
abstract: Based on sequence similarity, the sp7 gene product, MscSP, of the sulfur-compound-decomposing Gram-negative marine bacterium Silicibacter pomeroyi belongs to the family of MscS-type mechanosensitive channels. To investigate MscSP channel properties, we measured its response to membrane tension using the patch-clamp technique on either a heterologous expression system using giant spheroplasts of MJF465 Escherichia coli strain (devoid of mechanosensitive channels MscL, MscS, and MscK), or on purified MscSP protein reconstituted in azolectin liposomes. These experiments showed typical pressure-dependent gating properties of a stretch-activated channel with a current/voltage plot indicating a rectifying behavior and weak preference for anions similar to the MscS channel of E. coli. However, the MscSP channel exhibited functional differences with respect to conductance and desensitization behavior, with the most striking difference between the two channels being the lack of inactivation in MscSP compared with MscS. This seems to result from the fact that although MscSP has a Gly in an equivalent position to MscS (G113), a position that is critical for inactivation, MscSP has a Glu residue instead of an Asn in a position that was recently shown to allosterically influence MscS inactivation, N117. To our knowledge, this study describes the first electrophysiological characterization of an MscS-like channel from a marine bacterium belonging to sulfur-degrading α-proteobacteria.
authors.affiliation: Victor Chang Cardiac Research Institute, Darlinghurst, Australia. petrov67@gmail.com
authors.forename: Evgeny
authors.initials: E
authors.lastname: Petrov
authors.forename: Dinesh
authors.initials: D
authors.lastname: Palanivelu
authors.forename: Maryrose
authors.initials: M
authors.lastname: Constantine
authors.forename: Paul R
authors.initials: PR
authors.lastname: Rohde
authors.forename: Charles D
authors.initials: CD
authors.lastname: Cox
authors.forename: Takeshi
authors.initials: T
authors.lastname: Nomura
authors.forename: Daniel L
authors.initials: DL
authors.lastname: Minor
authors.forename: Boris
authors.initials: B
authors.lastname: Martinac
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism*; D040542:Mechanotransduction, Cellular; D008565:Membrane Proteins / Q000737:chemistry / Q000378:metabolism*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D018408:Patch-Clamp Techniques; D017433:Protein Structure, Secondary; D041902:Rhodobacteraceae / Q000166:cytology* / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid
chemical_list: D001426:Bacterial Proteins; D008565:Membrane Proteins
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