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

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.

Stability of the chaperonin system GroEL–GroES under extreme environmental conditions

“…Differently, marked stabilizing effects of some monomeric proteins (e.g., SNase, RNase A) by TMAO against pressureinduced unfolding and favorable effects of TMAO on enzyme function, protein polymerization and channel activity under high-pressure stress have been reported. 41,[56][57][58][59][60][61][62][63] The minor (possibly stabilizing) effect observed here is probably due to a smaller degree of unfolding and exposure of solvent accessible surface area (SASA), rendering the excluded volume effect imposed by TMAO less effective.…”

High Hydrostatic Pressure Inducible Trimethylamine N-Oxide Reductase Improves the Pressure Tolerance of Piezosensitive Bacteria Vibrio fluvialis

“…In this study, for the first time, we reported that TMAO facilitates the growth of QY27 under the HHP condition and confers on the piezo-sensitive strain a piezophilic-like phenotype. It has been reported that as one of the most important osmolytes in deep-sea fishes, TMAO protects the cells against low temperature and HHP ( Yancey et al, 1982 ; Saad-Nehme et al, 2001 ; Zou et al, 2002 ; He et al, 2009 ; Petrov et al, 2012 ). Here, as revealed by real-time Raman spectra analysis, genetic and biochemical analysis, TMAO is utilized by QY27 as an electron acceptor of TMAO anaerobic respiration and TMAO reductase TorA is critical for the TMAO-improved pressure tolerance.…”

“…TMAO can be produced through oxidation of TMA by a variety of marine bacteria, phytoplankton, invertebrates and fishes ( Barrett and Kwan, 1985 ; Seibel and Walsh, 2002 ; McCrindle et al, 2005 ). It accumulates in the tissue of marine animals and serves to protect against osmotic stress, adverse effects of low temperature, high concentration of urea and HHP ( Yancey et al, 1982 ; Saad-Nehme et al, 2001 ; Zou et al, 2002 ; He et al, 2009 ; Petrov et al, 2012 ). The tissue concentration of TMAO increases proportionally with the depth where the fish lives, and the upper limit of the predicated isosmotic state created by TMAO at 8,200 m has been considered a biochemistry restriction that accounts for the absence of fish in the deepest 25% of the ocean (8,400–11,000 m) ( Gillett et al, 1997 ; Yancey et al, 2014 ).…”

Co-evolution of proteins and solutions: protein adaptation versus cytoprotective micromolecules and their roles in marine organisms

“…Thus the effect of TMAO may be universal and independent of LDH intrinsic adaptations to pressure (Yancey and Siebenaller, 1999). Similarly, that piezolyte effects may be universal is also indicated by TMAO's ability to protect against pressure inhibition of yeast growth (Yancey et al, 2002) and a bacterial membrane channel (Petrov et al, 2012). With another model protein, staphylococcal nuclease (SNase) with TMAO studied by X-ray scattering, Krywka et al (2008) reported: 'A drastic stabilization is observed for the osmolyte TMAO, which exhibits not only a significant stabilization against temperatureinduced unfolding, but also a particularly strong stabilization of the protein against pressure.'…”