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  • 1
    Publication Date: 2016-03-26
    Description: In eukaryotes, P-type adenosine triphosphatases (ATPases) generate the plasma membrane potential and drive secondary transport systems; however, despite their importance, their regulation remains poorly understood. We monitored at the single-molecule level the activity of the prototypic proton-pumping P-type ATPase Arabidopsis thaliana isoform 2 (AHA2). Our measurements, combined with a physical nonequilibrium model of vesicle acidification, revealed that pumping is stochastically interrupted by long-lived (~100 seconds) inactive or leaky states. Allosteric regulation by pH gradients modulated the switch between these states but not the pumping or leakage rates. The autoinhibitory regulatory domain of AHA2 reduced the intrinsic pumping rates but increased the dwell time in the active pumping state. We anticipate that similar functional dynamics underlie the operation and regulation of many other active transporters.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Veshaguri, Salome -- Christensen, Sune M -- Kemmer, Gerdi C -- Ghale, Garima -- Moller, Mads P -- Lohr, Christina -- Christensen, Andreas L -- Justesen, Bo H -- Jorgensen, Ida L -- Schiller, Jurgen -- Hatzakis, Nikos S -- Grabe, Michael -- Pomorski, Thomas Gunther -- Stamou, Dimitrios -- R21-GM100224/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 2016 Mar 25;351(6280):1469-73. doi: 10.1126/science.aad6429.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Bionanotecnology and Nanomedicine Laboratory, University of Copenhagen, Copenhagen, Denmark. Department of Chemistry, University of Copenhagen, Copenhagen, Denmark. Nano-Science Center, University of Copenhagen, Copenhagen, Denmark. Lundbeck Foundation Center Biomembranes in Nanomedicine, University of Copenhagen, Copenhagen, Denmark. ; Centre for Membrane Pumps in Cells and Disease - PUMPKIN, Department of Plant and Environmental Sciences, University of Copenhagen, Frederiksberg Denmark. ; Institute of Medical Physics and Biophysics, Faculty of Medicine, University of Leipzig, Leipzig, Germany. ; Cardiovascular Research Institute, Department of Pharmaceutical Chemistry, University of California, San Francisco, CA 94143, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/27013734" target="_blank"〉PubMed〈/a〉
    Keywords: Allosteric Regulation ; Arabidopsis Proteins/antagonists & inhibitors/chemistry/*metabolism ; Hydrogen-Ion Concentration ; Ion Transport ; Membrane Potentials/drug effects/physiology ; Molecular Imaging ; Protein Structure, Tertiary ; Proton-Translocating ATPases/antagonists & inhibitors/chemistry/*metabolism ; *Protons ; Valinomycin/pharmacology
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 2
    Publication Date: 2014-07-06
    Description: Activation of the small guanosine triphosphatase H-Ras by the exchange factor Son of Sevenless (SOS) is an important hub for signal transduction. Multiple layers of regulation, through protein and membrane interactions, govern activity of SOS. We characterized the specific activity of individual SOS molecules catalyzing nucleotide exchange in H-Ras. Single-molecule kinetic traces revealed that SOS samples a broad distribution of turnover rates through stochastic fluctuations between distinct, long-lived (more than 100 seconds), functional states. The expected allosteric activation of SOS by Ras-guanosine triphosphate (GTP) was conspicuously absent in the mean rate. However, fluctuations into highly active states were modulated by Ras-GTP. This reveals a mechanism in which functional output may be determined by the dynamical spectrum of rates sampled by a small number of enzymes, rather than the ensemble average.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4255705/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4255705/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Iversen, Lars -- Tu, Hsiung-Lin -- Lin, Wan-Chen -- Christensen, Sune M -- Abel, Steven M -- Iwig, Jeff -- Wu, Hung-Jen -- Gureasko, Jodi -- Rhodes, Christopher -- Petit, Rebecca S -- Hansen, Scott D -- Thill, Peter -- Yu, Cheng-Han -- Stamou, Dimitrios -- Chakraborty, Arup K -- Kuriyan, John -- Groves, Jay T -- P01 AI091580/AI/NIAID NIH HHS/ -- R01 AI104789/AI/NIAID NIH HHS/ -- Howard Hughes Medical Institute/ -- New York, N.Y. -- Science. 2014 Jul 4;345(6192):50-4. doi: 10.1126/science.1250373.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Howard Hughes Medical Institute, Department of Chemistry, University of California, Berkeley, Berkeley, CA 94720, USA. ; Department of Chemical Engineering, Massachusetts Institute of Technology (MIT), Cambridge, MA 02139, USA. ; Howard Hughes Medical Institute, Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA. ; Department of Mechanical Engineering, University of California, Berkeley, Berkeley, CA 94720, USA. ; Department of Chemistry, MIT, Cambridge, MA 02139, USA. ; Mechanobiology Institute, National University of Singapore, Singapore. ; Department of Chemistry and Nano-Science Center, University of Copenhagen, Copenhagen, Denmark. ; Department of Chemical Engineering, Massachusetts Institute of Technology (MIT), Cambridge, MA 02139, USA. Department of Chemistry, MIT, Cambridge, MA 02139, USA. Department of Biological Engineering, MIT, Cambridge, MA 02139, USA. Ragon Institute of Massachusetts General Hospital, MIT, and Harvard, Cambridge, MA 02139, USA. Department of Physics, MIT, Cambridge, MA 02139, USA. Institute for Medical Engineering and Science, MIT, Cambridge, MA 02139, USA. ; Howard Hughes Medical Institute, Department of Chemistry, University of California, Berkeley, Berkeley, CA 94720, USA. Howard Hughes Medical Institute, Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA. Physical Biosciences and Materials Sciences Divisions, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA. ; Howard Hughes Medical Institute, Department of Chemistry, University of California, Berkeley, Berkeley, CA 94720, USA. Mechanobiology Institute, National University of Singapore, Singapore. Physical Biosciences and Materials Sciences Divisions, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA. Berkeley Education Alliance for Research in Singapore, 1 Create Way, CREATE tower level 11, University Town, Singapore 138602. jtgroves@lbl.gov.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/24994643" target="_blank"〉PubMed〈/a〉
    Keywords: Allosteric Regulation ; Catalytic Domain ; Crystallography, X-Ray ; Enzyme Activation ; Humans ; Kinetics ; Nucleotides/chemistry ; *Protein Interaction Domains and Motifs ; Proto-Oncogene Proteins p21(ras)/*agonists ; Son of Sevenless Protein, Drosophila/*chemistry/genetics
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 3
    Publication Date: 1998-04-29
    Description: Lateral force microscopy in the wearless regime was used to study the friction behavior of a lipid monolayer on mica. In the monolayer, condensed domains with long-range orientational order of the lipid molecules were present. The domains revealed unexpectedly strong friction anisotropies and non-negligible friction asymmetries. The angular dependency of these effects correlated well with the tilt direction of the alkyl chains of the monolayer, as determined by electron diffraction and Brewster angle microscopy. The molecular tilt causing these frictional effects was less than 15 degrees, demonstrating that even small molecular tilts can make a major contribution to friction.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Liley -- Gourdon -- Stamou -- Meseth -- Fischer -- Lautz -- Stahlberg -- Vogel -- Burnham -- Duschl -- New York, N.Y. -- Science. 1998 Apr 10;280(5361):273-5.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉M. Liley, D. Stamou, U. Meseth, H. Vogel, C. Duschl, Department of Chemistry, Swiss Federal Institute of Technology, CH-1015 Lausanne, Switzerland. D. Gourdon and N. A. Burnham, Department of Physics, Swiss Federal Institute of Technology, CH-1015.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9535654" target="_blank"〉PubMed〈/a〉
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 4
    ISSN: 1573-2711
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract We performed lateral force microscopy on thiolipid Langmuir-Blodgett (LB) films physisorbed on mica substrates with asilicon tip of an atomic force microscope. The structure ofcondensed domains, reflecting their symmetric morphology, wasobserved. The lateral (friction) forces were measured as a function of (normal) applied load, of sliding velocity and of themolecular orientation of these films. We found that at a fixedvelocity, lateral force increases with applied load in a linearfashion. Within the velocity range 0.01 to~50μm/s, the lateral force signal initiallyincreases monotonically with velocity (static regime) and thenstabilises when the tip begins sliding. The friction force andthe observed asymmetry in the quasi-static ``friction-loops''(torsion of the tip during a forward/reverse scan) were foundto be dependent on the domain orientation with respect to the scan direction, while the measured adhesive force remainedconstant. Together, friction and asymmetry reveal and mapmolecular packing and tilt.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract. A bifacial topological template exhibiting metal-binding sites and thioalkane chains has been incorporated into self-assembled monolayers and immobilised on gold surfaces: These systems allow for the detection of external ligands by SPR spectroscopy representing a first step in developing biosensors based on the TASP (Template Assembled Synthetic Proteins) concept.
    Type of Medium: Electronic Resource
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