The protective effect of osmoprotectant TMAO on bacterial mechanosensitive channels of small conductance MscS/MscK under high hydrostatic pressure.

Victor Chang Cardiac Research Institute; Darlinghurst, NSW Australia.
Channels (Austin, Tex.) (Impact Factor: 2.32). 07/2012; 6(4). DOI: 10.4161/chan.20833
Source: PubMed

ABSTRACT Activity of the bacterial mechanosensitive channels of small conductance MscS/MscK of E. coli was investigated under high hydrostatic pressure (HHP) using the "flying-patch" patch-clamp technique. The channels were gated by negative pipette voltage and their open probability was measured at HHP of 0.1 to 80 MPa. The channel open probability decreased with increasing HHP. When the osmolyte methylamine N-oxide (TMAO) was applied to the cytoplasmic side of the inside-out excised membrane patches of E. coli giant spheroplasts the inhibitory effect of HHP on the channel activity was suppressed at pressures of up to 40 MPa. At 40 MPa and above the channel open probability decreased in a similar fashion with or without TMAO. Our study suggests that TMAO helps to counteract the effect of HHP up to 40 MPa on the MscS/MscK open state by "shielding" the cytoplasmic domain of the channels.

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    ABSTRACT: Mechanosensitive (MS) ion channels are to date the best characterized biological force-sensing systems. They present the best example of coupling protein conformations to the mechanics of the surrounding cell membrane. Studies of MS channels conducted over the last 28 years have from their serendipitous discovery ( 1) (,) ( 2) and confusion about their artifactual nature ( 3) to their molecular identification ( 4) (-) ( 6) and structural determination ( 7) (-) ( 10) greatly contributed to our understanding of molecular mechanisms underlying the physiology of mechanosensory transduction.
    Channels (Austin, Tex.) 07/2012; 6(4). · 2.32 Impact Factor
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May 21, 2014