The Experts below are selected from a list of 98898 Experts worldwide ranked by ideXlab platform
David J E Callaway - One of the best experts on this subject based on the ideXlab platform.
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nanoscale protein Domain motion and long range allostery in signaling proteins a view from neutron spin echo spectroscopy
Biophysical Reviews, 2015Co-Authors: David J E Callaway, Zimei BuAbstract:Many cellular proteins are multi-Domain proteins. Coupled Domain–Domain interactions in these multiDomain proteins are important for the allosteric relay of signals in the cellular signaling networks. We have initiated the application of neutron spin echo spectroscopy to the study of nanoscale protein Domain motions on submicrosecond time scales and on nanometer length scale. Our NSE experiments reveal the activation of protein Domain motions over a long distance of over more than 100 A in a multiDomain scaffolding protein NHERF1 upon binding to another protein, Ezrin. Such activation of nanoscale protein Domain motions is correlated with the allosteric assembly of multi-protein complexes by NHERF1 and Ezrin. Here, we summarize the theoretical framework that we have developed, which uses simple concepts from nonequilibrium statistical mechanics to interpret the NSE data, and employs a mobility tensor to describe nanoscale protein Domain motion. Extracting nanoscale protein Domain motion from the NSE does not require elaborate molecular dynamics simulations, nor complex fits to rotational motion, nor elastic network models. The approach is thus more robust than multiparameter techniques that require untestable assumptions. We also demonstrate that an experimental scheme of selective deuteration of a protein subunit in a complex can highlight and amplify specific Domain dynamics from the abundant global translational and rotational motions in a protein. We expect NSE to provide a unique tool to determine nanoscale protein dynamics for the understanding of protein functions, such as how signals are propagated in a protein over a long distance to a distal Domain.
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activation of nanoscale allosteric protein Domain motion revealed by neutron spin echo spectroscopy
Biophysical Journal, 2010Co-Authors: B Farago, David J E Callaway, Jianquan Li, Gabriel Cornilescu, Zimei BuAbstract:NHERF1 is a multiDomain scaffolding protein that assembles signaling complexes, and regulates the cell surface expression and endocytic recycling of a variety of membrane proteins. The ability of the two PDZ Domains in NHERF1 to assemble protein complexes is allosterically modulated by the membrane-cytoskeleton linker protein ezrin, whose binding site is located as far as 110 Angstroms away from the PDZ Domains. Here, using neutron spin echo (NSE) spectroscopy, selective deuterium labeling, and theoretical analyses, we reveal the activation of interDomain motion in NHERF1 on nanometer length-scales and on submicrosecond timescales upon forming a complex with ezrin. We show that a much-simplified coarse-grained model suffices to describe interDomain motion of a multiDomain protein or protein complex. We expect that future NSE experiments will benefit by exploiting our approach of selective deuteration to resolve the specific Domain motions of interest from a plethora of global translational and rotational motions. Our results demonstrate that the dynamic propagation of allosteric signals to distal sites involves changes in long-range Coupled Domain motions on submicrosecond timescales, and that these Coupled motions can be distinguished and characterized by NSE.
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Coupled protein Domain motion in taq polymerase revealed by neutron spin echo spectroscopy
Proceedings of the National Academy of Sciences of the United States of America, 2005Co-Authors: Zimei Bu, Ralf Biehl, M Monkenbusch, D Richter, David J E CallawayAbstract:Long-range conformational changes in proteins are ubiquitous in biology for the transmission and amplification of signals; such conformational changes can be triggered by small-amplitude, nanosecond protein Domain motion. Understanding how conformational changes are initiated requires the characterization of protein Domain motion on these timescales and on length scales comparable to protein dimensions. Using neutron spin-echo spectroscopy (NSE), normal mode analysis, and a statistical-mechanical framework, we reveal overdamped, Coupled Domain motion within DNA polymerase I from Thermus aquaticus (Taq polymerase). This protein utilizes correlated Domain dynamics over 70 A to coordinate nucleotide synthesis and cleavage during DNA synthesis and repair. We show that NSE spectroscopy can determine the Domain mobility tensor, which determines the degree of dynamical coupling between Domains. The mobility tensor defines the Domain velocity response to a force applied to it or to another Domain, just as the sails of a sailboat determine its velocity given the applied wind force. The NSE results provide insights into the nature of protein Domain motion that are not appreciated by conventional biophysical techniques.
Zimei Bu - One of the best experts on this subject based on the ideXlab platform.
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nanoscale protein Domain motion and long range allostery in signaling proteins a view from neutron spin echo spectroscopy
Biophysical Reviews, 2015Co-Authors: David J E Callaway, Zimei BuAbstract:Many cellular proteins are multi-Domain proteins. Coupled Domain–Domain interactions in these multiDomain proteins are important for the allosteric relay of signals in the cellular signaling networks. We have initiated the application of neutron spin echo spectroscopy to the study of nanoscale protein Domain motions on submicrosecond time scales and on nanometer length scale. Our NSE experiments reveal the activation of protein Domain motions over a long distance of over more than 100 A in a multiDomain scaffolding protein NHERF1 upon binding to another protein, Ezrin. Such activation of nanoscale protein Domain motions is correlated with the allosteric assembly of multi-protein complexes by NHERF1 and Ezrin. Here, we summarize the theoretical framework that we have developed, which uses simple concepts from nonequilibrium statistical mechanics to interpret the NSE data, and employs a mobility tensor to describe nanoscale protein Domain motion. Extracting nanoscale protein Domain motion from the NSE does not require elaborate molecular dynamics simulations, nor complex fits to rotational motion, nor elastic network models. The approach is thus more robust than multiparameter techniques that require untestable assumptions. We also demonstrate that an experimental scheme of selective deuteration of a protein subunit in a complex can highlight and amplify specific Domain dynamics from the abundant global translational and rotational motions in a protein. We expect NSE to provide a unique tool to determine nanoscale protein dynamics for the understanding of protein functions, such as how signals are propagated in a protein over a long distance to a distal Domain.
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activation of nanoscale allosteric protein Domain motion revealed by neutron spin echo spectroscopy
Biophysical Journal, 2010Co-Authors: B Farago, David J E Callaway, Jianquan Li, Gabriel Cornilescu, Zimei BuAbstract:NHERF1 is a multiDomain scaffolding protein that assembles signaling complexes, and regulates the cell surface expression and endocytic recycling of a variety of membrane proteins. The ability of the two PDZ Domains in NHERF1 to assemble protein complexes is allosterically modulated by the membrane-cytoskeleton linker protein ezrin, whose binding site is located as far as 110 Angstroms away from the PDZ Domains. Here, using neutron spin echo (NSE) spectroscopy, selective deuterium labeling, and theoretical analyses, we reveal the activation of interDomain motion in NHERF1 on nanometer length-scales and on submicrosecond timescales upon forming a complex with ezrin. We show that a much-simplified coarse-grained model suffices to describe interDomain motion of a multiDomain protein or protein complex. We expect that future NSE experiments will benefit by exploiting our approach of selective deuteration to resolve the specific Domain motions of interest from a plethora of global translational and rotational motions. Our results demonstrate that the dynamic propagation of allosteric signals to distal sites involves changes in long-range Coupled Domain motions on submicrosecond timescales, and that these Coupled motions can be distinguished and characterized by NSE.
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Coupled protein Domain motion in taq polymerase revealed by neutron spin echo spectroscopy
Proceedings of the National Academy of Sciences of the United States of America, 2005Co-Authors: Zimei Bu, Ralf Biehl, M Monkenbusch, D Richter, David J E CallawayAbstract:Long-range conformational changes in proteins are ubiquitous in biology for the transmission and amplification of signals; such conformational changes can be triggered by small-amplitude, nanosecond protein Domain motion. Understanding how conformational changes are initiated requires the characterization of protein Domain motion on these timescales and on length scales comparable to protein dimensions. Using neutron spin-echo spectroscopy (NSE), normal mode analysis, and a statistical-mechanical framework, we reveal overdamped, Coupled Domain motion within DNA polymerase I from Thermus aquaticus (Taq polymerase). This protein utilizes correlated Domain dynamics over 70 A to coordinate nucleotide synthesis and cleavage during DNA synthesis and repair. We show that NSE spectroscopy can determine the Domain mobility tensor, which determines the degree of dynamical coupling between Domains. The mobility tensor defines the Domain velocity response to a force applied to it or to another Domain, just as the sails of a sailboat determine its velocity given the applied wind force. The NSE results provide insights into the nature of protein Domain motion that are not appreciated by conventional biophysical techniques.
Serban Lepadatu - One of the best experts on this subject based on the ideXlab platform.
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synthetic ferrimagnet nanowires with very low critical current density for Coupled Domain wall motion
Scientific Reports, 2017Co-Authors: Serban Lepadatu, Henri Saarikoski, Robert Beacham, M J Benitez, T A Moore, G Burnell, Satoshi Sugimoto, Daniel YesudasAbstract:Domain walls in ferromagnetic nanowires are potential building-blocks of future technologies such as racetrack memories, in which data encoded in the Domain walls are transported using spin-polarised currents. However, the development of energy-efficient devices has been hampered by the high current densities needed to initiate Domain wall motion. We show here that a remarkable reduction in the critical current density can be achieved for in-plane magnetised Coupled Domain walls in CoFe/Ru/CoFe synthetic ferrimagnet tracks. The antiferromagnetic exchange coupling between the layers leads to simple Neel wall structures, imaged using photoemission electron and Lorentz transmission electron microscopy, with a width of only ~100 nm. The measured critical current density to set these walls in motion, detected using magnetotransport measurements, is 1.0 × 1011 Am−2, almost an order of magnitude lower than in a ferromagnetically Coupled control sample. Theoretical modelling indicates that this is due to nonadiabatic driving of anisotropically Coupled walls, a mechanism that can be used to design efficient Domain-wall devices.
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very low critical current density for motion of Coupled Domain walls in synthetic ferrimagnet nanowires
arXiv: Mesoscale and Nanoscale Physics, 2016Co-Authors: Serban Lepadatu, Henri Saarikoski, Robert Beacham, M J Benitez, T A Moore, G Burnell, Satoshi Sugimoto, Daniel Yesudas, May C Wheeler, J MiguelAbstract:Domain walls in ferromagnetic nanowires are potential building-blocks of future technologies such as racetrack memories, in which data encoded in the Domain walls are transported using spin-polarised currents. However, the development of energy-efficient devices has been hampered by the high current densities needed to initiate Domain wall motion. We show here that a remarkable reduction in the critical current density can be achieved for in-plane magnetised Coupled Domain walls in CoFe/Ru/CoFe synthetic ferrimagnet tracks. The antiferromagnetic exchange coupling between the layers leads to simple Neel wall structures, imaged using photoemission electron and Lorentz transmission electron microscopy, with a width of only $\sim 100$~nm. The measured critical current density to set these walls in motion, detected using magnetotransport measurements, is $1.0 \times 10^{11}$~Am$^{-2}$, almost an order of magnitude lower than in a ferromagnetically Coupled control sample. Theoretical modelling indicates that this is due to nonadiabatic driving of anisotropically Coupled walls, a mechanism that can be used to design efficient Domain-wall devices.
Jacob Linder - One of the best experts on this subject based on the ideXlab platform.
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universal absence of walker breakdown and linear current velocity relation via spin orbit torques in Coupled and single Domain wall motion
Physical Review B, 2017Co-Authors: Vetle Risinggard, Jacob LinderAbstract:We consider theoretically Domain wall motion driven by spin-orbit and spin Hall torques. We find that it is possible to achieve universal absence of Walker breakdown for all spin-orbit torques using experimentally relevant spin-orbit coupling strengths. For spin-orbit torques other than the pure Rashba spin-orbit torque, this gives a linear current-velocity relation instead of a saturation of the velocity at high current densities. The effect is very robust and is found in both soft and hard magnetic materials, as well as in the presence of the Dzyaloshinskii-Moriya interaction and in Coupled Domain walls in synthetic antiferromagnets, where it leads to very high Domain wall velocities. Moreover, recent experiments have demonstrated that the switching of a synthetic antiferromagnet does not obey the usual spin Hall angle dependence, but that Domain expansion and contraction can be selectively controlled toggling only the applied in-plane magnetic field magnitude and not its sign. We show that the combination of spin Hall torques and interlayer exchange coupling produces the necessary relative velocities for this switching to occur.
Daniel Yesudas - One of the best experts on this subject based on the ideXlab platform.
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synthetic ferrimagnet nanowires with very low critical current density for Coupled Domain wall motion
Scientific Reports, 2017Co-Authors: Serban Lepadatu, Henri Saarikoski, Robert Beacham, M J Benitez, T A Moore, G Burnell, Satoshi Sugimoto, Daniel YesudasAbstract:Domain walls in ferromagnetic nanowires are potential building-blocks of future technologies such as racetrack memories, in which data encoded in the Domain walls are transported using spin-polarised currents. However, the development of energy-efficient devices has been hampered by the high current densities needed to initiate Domain wall motion. We show here that a remarkable reduction in the critical current density can be achieved for in-plane magnetised Coupled Domain walls in CoFe/Ru/CoFe synthetic ferrimagnet tracks. The antiferromagnetic exchange coupling between the layers leads to simple Neel wall structures, imaged using photoemission electron and Lorentz transmission electron microscopy, with a width of only ~100 nm. The measured critical current density to set these walls in motion, detected using magnetotransport measurements, is 1.0 × 1011 Am−2, almost an order of magnitude lower than in a ferromagnetically Coupled control sample. Theoretical modelling indicates that this is due to nonadiabatic driving of anisotropically Coupled walls, a mechanism that can be used to design efficient Domain-wall devices.
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very low critical current density for motion of Coupled Domain walls in synthetic ferrimagnet nanowires
arXiv: Mesoscale and Nanoscale Physics, 2016Co-Authors: Serban Lepadatu, Henri Saarikoski, Robert Beacham, M J Benitez, T A Moore, G Burnell, Satoshi Sugimoto, Daniel Yesudas, May C Wheeler, J MiguelAbstract:Domain walls in ferromagnetic nanowires are potential building-blocks of future technologies such as racetrack memories, in which data encoded in the Domain walls are transported using spin-polarised currents. However, the development of energy-efficient devices has been hampered by the high current densities needed to initiate Domain wall motion. We show here that a remarkable reduction in the critical current density can be achieved for in-plane magnetised Coupled Domain walls in CoFe/Ru/CoFe synthetic ferrimagnet tracks. The antiferromagnetic exchange coupling between the layers leads to simple Neel wall structures, imaged using photoemission electron and Lorentz transmission electron microscopy, with a width of only $\sim 100$~nm. The measured critical current density to set these walls in motion, detected using magnetotransport measurements, is $1.0 \times 10^{11}$~Am$^{-2}$, almost an order of magnitude lower than in a ferromagnetically Coupled control sample. Theoretical modelling indicates that this is due to nonadiabatic driving of anisotropically Coupled walls, a mechanism that can be used to design efficient Domain-wall devices.
