The Experts below are selected from a list of 6483 Experts worldwide ranked by ideXlab platform

Boris Martinac - One of the best experts on this subject based on the ideXlab platform.

  • the role of the periplasmic loop residue glutamine 65 for mscl mechanosensitivity
    European Biophysics Journal, 2005
    Co-Authors: Ijung Tsai, John Rayment, Christel Norman, Allan J Mckinley, Boris Martinac
    Abstract:

    The periplasmic loop of MscL, the mechanosensitive channel of large conductance, acts as a spring resisting the opening of the channel. Recently, a high-throughput functional screening of a range of MscL structural mutants indicated that the substitution of residue glutamine (Q) 65 with arginine (R) or leucine (L) leads to a wild-type (WT)-like and a loss-of-function (LOF) phenotype, respectively (Maurer and Dougherty J. Biol. Chem. 278(23):21076–21082, 2003). We used electron paramagnetic resonance (EPR) spectroscopy, single-channel recording and in vivo experiments to investigate further the effect of R and L mutation of Q65 on the gating mechanism of MscL. Structural analysis of Q65R and Q65L was carried out by coupling the site-directed spin labeling (SDSL) with EPR spectroscopy. A SDSL cysteine mutant of the isoleucine 24 residue (I24C-SL) in the first transmembrane domain, TM1, of MscL served as a reporter residue in EPR experiments. This was due to its strong spin–spin interaction with the neighboring I24C-SL residues in the MscL channel pentamer (Perozo et al.Nature 418:942–948, 2002). The effects of bilayer incorporation of lysophosphatidylcholine on the MscL mutants were also investigated. Functional analysis was carried out using patch-clamp recordings from these mutants and WT MscL reconstituted into artificial liposomes. Although our data are largely in agreement with the high-throughput mutational analysis of Maurer and Dougherty, this study shows that Q65R and Q65L form functional channels and that these mutations lead to partial gain-of-function (GOF) and LOF mutation, respectively. Overall, our study confirms and advances the notion that the periplasmic loop plays a role in setting the channel mechanosensitivity.

  • the role of the periplasmic loop residue glutamine 65 for mscl
    2005
    Co-Authors: Ijung Tsai, John Rayment, Christel Norman, Allan J Mckinley, Boris Martinac
    Abstract:

    The periplasmic loop of MscL, the mechano- sensitive channel of large conductance, acts as a spring resisting the opening of the channel. Recently, a high- throughput functional screening of a range of MscL structural mutants indicated that the substitution of res- idue glutamine (Q) 65 with arginine (R) or leucine (L) leads to a wild-type (WT)-like and a loss-of-function (LOF) phenotype, respectively (Maurer and Dougherty J. Biol. Chem. 278(23):21076-21082, 2003). We used electron paramagnetic resonance (EPR) spectroscopy, single-channel recording and in vivo experiments to investigate further the effect of R and L mutation of Q65 on the gating mechanism of MscL. Structural analysis of Q65R and Q65L was carried out by coupling the site- directed spin labeling (SDSL) with EPR spectroscopy. A SDSL cysteine mutant of the isoleucine 24 residue (I24C- SL) in the first transmembrane domain, TM1, of MscL served as a reporter residue in EPR experiments. This was due to its strong spin-spin interaction with the neigh- boring I24C-SL residues in the MscL channel pentamer (Perozo et al.Nature 418:942-948, 2002). The effects of bilayer incorporation of lysophosphatidylcholine on the MscL mutants were also investigated. Functional analysis was carried out using patch-clamp recordings from these mutants and WT MscL reconstituted into artificial liposomes. Although our data are largely in agreement with the high-throughput mutational analysis of Maurer and Dougherty, this study shows that Q65R and Q65L form functional channels and that these mutations lead to partial gain-of-function (GOF) and LOF mutation, respectively. Overall, our study confirms and advances the notion that the periplasmic loop plays a role in setting the channel mechanosensitivity.

Ijung Tsai - One of the best experts on this subject based on the ideXlab platform.

  • the role of the periplasmic loop residue glutamine 65 for mscl mechanosensitivity
    European Biophysics Journal, 2005
    Co-Authors: Ijung Tsai, John Rayment, Christel Norman, Allan J Mckinley, Boris Martinac
    Abstract:

    The periplasmic loop of MscL, the mechanosensitive channel of large conductance, acts as a spring resisting the opening of the channel. Recently, a high-throughput functional screening of a range of MscL structural mutants indicated that the substitution of residue glutamine (Q) 65 with arginine (R) or leucine (L) leads to a wild-type (WT)-like and a loss-of-function (LOF) phenotype, respectively (Maurer and Dougherty J. Biol. Chem. 278(23):21076–21082, 2003). We used electron paramagnetic resonance (EPR) spectroscopy, single-channel recording and in vivo experiments to investigate further the effect of R and L mutation of Q65 on the gating mechanism of MscL. Structural analysis of Q65R and Q65L was carried out by coupling the site-directed spin labeling (SDSL) with EPR spectroscopy. A SDSL cysteine mutant of the isoleucine 24 residue (I24C-SL) in the first transmembrane domain, TM1, of MscL served as a reporter residue in EPR experiments. This was due to its strong spin–spin interaction with the neighboring I24C-SL residues in the MscL channel pentamer (Perozo et al.Nature 418:942–948, 2002). The effects of bilayer incorporation of lysophosphatidylcholine on the MscL mutants were also investigated. Functional analysis was carried out using patch-clamp recordings from these mutants and WT MscL reconstituted into artificial liposomes. Although our data are largely in agreement with the high-throughput mutational analysis of Maurer and Dougherty, this study shows that Q65R and Q65L form functional channels and that these mutations lead to partial gain-of-function (GOF) and LOF mutation, respectively. Overall, our study confirms and advances the notion that the periplasmic loop plays a role in setting the channel mechanosensitivity.

  • the role of the periplasmic loop residue glutamine 65 for mscl
    2005
    Co-Authors: Ijung Tsai, John Rayment, Christel Norman, Allan J Mckinley, Boris Martinac
    Abstract:

    The periplasmic loop of MscL, the mechano- sensitive channel of large conductance, acts as a spring resisting the opening of the channel. Recently, a high- throughput functional screening of a range of MscL structural mutants indicated that the substitution of res- idue glutamine (Q) 65 with arginine (R) or leucine (L) leads to a wild-type (WT)-like and a loss-of-function (LOF) phenotype, respectively (Maurer and Dougherty J. Biol. Chem. 278(23):21076-21082, 2003). We used electron paramagnetic resonance (EPR) spectroscopy, single-channel recording and in vivo experiments to investigate further the effect of R and L mutation of Q65 on the gating mechanism of MscL. Structural analysis of Q65R and Q65L was carried out by coupling the site- directed spin labeling (SDSL) with EPR spectroscopy. A SDSL cysteine mutant of the isoleucine 24 residue (I24C- SL) in the first transmembrane domain, TM1, of MscL served as a reporter residue in EPR experiments. This was due to its strong spin-spin interaction with the neigh- boring I24C-SL residues in the MscL channel pentamer (Perozo et al.Nature 418:942-948, 2002). The effects of bilayer incorporation of lysophosphatidylcholine on the MscL mutants were also investigated. Functional analysis was carried out using patch-clamp recordings from these mutants and WT MscL reconstituted into artificial liposomes. Although our data are largely in agreement with the high-throughput mutational analysis of Maurer and Dougherty, this study shows that Q65R and Q65L form functional channels and that these mutations lead to partial gain-of-function (GOF) and LOF mutation, respectively. Overall, our study confirms and advances the notion that the periplasmic loop plays a role in setting the channel mechanosensitivity.

Ola P G Persson - One of the best experts on this subject based on the ideXlab platform.

  • similarity theory based on the Dougherty ozmidov length scale
    Quarterly Journal of the Royal Meteorological Society, 2015
    Co-Authors: Peter S. Guest, Alexey A Grachev, Christopher W. Fairall, Edgar L. Andreas, Ola P G Persson
    Abstract:

    This article describes a local similarity theory for developed turbulence in the stably stratified boundary layer that is based on the Brunt–Vaisala frequency and the dissipation rate of turbulent kinetic energy instead of the turbulent fluxes used in the traditional Monin–Obukhov similarity theory. Based on dimensional analysis (Pi theorem), it is shown that any properly scaled statistics of the small-scale turbulence are universal functions of a stability parameter defined as the ratio of a reference height z and the Dougherty–Ozmidov length scale, which in the limit of z-less stratification is linearly proportional to the Obukhov length scale. Measurements of atmospheric turbulence made at five levels on a 20 m tower over the Arctic pack ice during the Surface Heat Budget of the Arctic Ocean experiment (SHEBA) are used to examine the behaviour of different similarity functions in the stable boundary layer. In the framework of this approach the non-dimensional turbulent viscosity is equal to the gradient Richardson number, whereas the non-dimensional turbulent thermal diffusivity is equal to the flux Richardson number. These results are a consequence of the approximate local balance between production of turbulence by shear in the mean flow and viscous dissipation. The turbulence framework based on the Brunt–Vaisala frequency and the dissipation rate of turbulent kinetic energy may have practical advantages for estimating turbulence when the fluxes are not directly available.

John Rayment - One of the best experts on this subject based on the ideXlab platform.

  • the role of the periplasmic loop residue glutamine 65 for mscl mechanosensitivity
    European Biophysics Journal, 2005
    Co-Authors: Ijung Tsai, John Rayment, Christel Norman, Allan J Mckinley, Boris Martinac
    Abstract:

    The periplasmic loop of MscL, the mechanosensitive channel of large conductance, acts as a spring resisting the opening of the channel. Recently, a high-throughput functional screening of a range of MscL structural mutants indicated that the substitution of residue glutamine (Q) 65 with arginine (R) or leucine (L) leads to a wild-type (WT)-like and a loss-of-function (LOF) phenotype, respectively (Maurer and Dougherty J. Biol. Chem. 278(23):21076–21082, 2003). We used electron paramagnetic resonance (EPR) spectroscopy, single-channel recording and in vivo experiments to investigate further the effect of R and L mutation of Q65 on the gating mechanism of MscL. Structural analysis of Q65R and Q65L was carried out by coupling the site-directed spin labeling (SDSL) with EPR spectroscopy. A SDSL cysteine mutant of the isoleucine 24 residue (I24C-SL) in the first transmembrane domain, TM1, of MscL served as a reporter residue in EPR experiments. This was due to its strong spin–spin interaction with the neighboring I24C-SL residues in the MscL channel pentamer (Perozo et al.Nature 418:942–948, 2002). The effects of bilayer incorporation of lysophosphatidylcholine on the MscL mutants were also investigated. Functional analysis was carried out using patch-clamp recordings from these mutants and WT MscL reconstituted into artificial liposomes. Although our data are largely in agreement with the high-throughput mutational analysis of Maurer and Dougherty, this study shows that Q65R and Q65L form functional channels and that these mutations lead to partial gain-of-function (GOF) and LOF mutation, respectively. Overall, our study confirms and advances the notion that the periplasmic loop plays a role in setting the channel mechanosensitivity.

  • the role of the periplasmic loop residue glutamine 65 for mscl
    2005
    Co-Authors: Ijung Tsai, John Rayment, Christel Norman, Allan J Mckinley, Boris Martinac
    Abstract:

    The periplasmic loop of MscL, the mechano- sensitive channel of large conductance, acts as a spring resisting the opening of the channel. Recently, a high- throughput functional screening of a range of MscL structural mutants indicated that the substitution of res- idue glutamine (Q) 65 with arginine (R) or leucine (L) leads to a wild-type (WT)-like and a loss-of-function (LOF) phenotype, respectively (Maurer and Dougherty J. Biol. Chem. 278(23):21076-21082, 2003). We used electron paramagnetic resonance (EPR) spectroscopy, single-channel recording and in vivo experiments to investigate further the effect of R and L mutation of Q65 on the gating mechanism of MscL. Structural analysis of Q65R and Q65L was carried out by coupling the site- directed spin labeling (SDSL) with EPR spectroscopy. A SDSL cysteine mutant of the isoleucine 24 residue (I24C- SL) in the first transmembrane domain, TM1, of MscL served as a reporter residue in EPR experiments. This was due to its strong spin-spin interaction with the neigh- boring I24C-SL residues in the MscL channel pentamer (Perozo et al.Nature 418:942-948, 2002). The effects of bilayer incorporation of lysophosphatidylcholine on the MscL mutants were also investigated. Functional analysis was carried out using patch-clamp recordings from these mutants and WT MscL reconstituted into artificial liposomes. Although our data are largely in agreement with the high-throughput mutational analysis of Maurer and Dougherty, this study shows that Q65R and Q65L form functional channels and that these mutations lead to partial gain-of-function (GOF) and LOF mutation, respectively. Overall, our study confirms and advances the notion that the periplasmic loop plays a role in setting the channel mechanosensitivity.

Alexey A Grachev - One of the best experts on this subject based on the ideXlab platform.

  • similarity theory based on the Dougherty ozmidov length scale
    Quarterly Journal of the Royal Meteorological Society, 2015
    Co-Authors: Peter S. Guest, Alexey A Grachev, Christopher W. Fairall, Edgar L. Andreas, Ola P G Persson
    Abstract:

    This article describes a local similarity theory for developed turbulence in the stably stratified boundary layer that is based on the Brunt–Vaisala frequency and the dissipation rate of turbulent kinetic energy instead of the turbulent fluxes used in the traditional Monin–Obukhov similarity theory. Based on dimensional analysis (Pi theorem), it is shown that any properly scaled statistics of the small-scale turbulence are universal functions of a stability parameter defined as the ratio of a reference height z and the Dougherty–Ozmidov length scale, which in the limit of z-less stratification is linearly proportional to the Obukhov length scale. Measurements of atmospheric turbulence made at five levels on a 20 m tower over the Arctic pack ice during the Surface Heat Budget of the Arctic Ocean experiment (SHEBA) are used to examine the behaviour of different similarity functions in the stable boundary layer. In the framework of this approach the non-dimensional turbulent viscosity is equal to the gradient Richardson number, whereas the non-dimensional turbulent thermal diffusivity is equal to the flux Richardson number. These results are a consequence of the approximate local balance between production of turbulence by shear in the mean flow and viscous dissipation. The turbulence framework based on the Brunt–Vaisala frequency and the dissipation rate of turbulent kinetic energy may have practical advantages for estimating turbulence when the fluxes are not directly available.

  • Similarity theory based on the Dougherty-Ozmidov length scale
    arXiv: Atmospheric and Oceanic Physics, 2014
    Co-Authors: Alexey A Grachev, Peter S. Guest, Christopher W. Fairall, Edgar L. Andreas, P. Ola G. Persson
    Abstract:

    Local similarity theory is suggested based on the Brunt-Vaisala frequency and the dissipation rate of turbulent kinetic energy instead the turbulent fluxes used in the traditional Monin-Obukhov similarity theory. Based on dimensional analysis (Pi theorem), it is shown that any properly scaled statistics of the small-scale turbulence are universal functions of a stability parameter defined as the ratio of a reference height z and the Dougherty-Ozmidov length scale which in the limit of z-less stratification is linearly proportional to the Obukhov length scale. Measurements of atmospheric turbulence made at five levels on a 20-m tower over the Arctic pack ice during the Surface Heat Budget of the Arctic Ocean experiment (SHEBA) are used to examine the behaviour of different similarity functions in the stable boundary layer. It is found that in the framework of this approach the non-dimensional turbulent viscosity is equal to the gradient Richardson number whereas the non-dimensional turbulent thermal diffusivity is equal to the flux Richardson number. These results are a consequence of the approximate local balance between production of turbulence by the mean flow shear and viscous dissipation. The turbulence framework based on the Brunt-Vaisala frequency and the dissipation rate of turbulent kinetic energy may have practical advantages for estimating turbulence when the fluxes are not directly available.