Faculty Opinions recommendation of General protein diffusion barriers create compartments within bacterial cells.

2013 ◽  
Author(s):  
Marc Lecuit ◽  
Serge Mostowy
Keyword(s):  
Diffusion Barriers ◽  
Bacterial Cells ◽  
Protein Diffusion ◽  
General Protein

scholarly journals General Protein Diffusion Barriers Create Compartments within Bacterial Cells

Cell ◽  
2012 ◽  
Vol 151 (6) ◽  
pp. 1270-1282 ◽  
Author(s):  
Susan Schlimpert ◽  
Eric A. Klein ◽  
Ariane Briegel ◽  
Velocity Hughes ◽  
Jörg Kahnt ◽  
...  
Keyword(s):  
Diffusion Barriers ◽  
Bacterial Cells ◽  
Protein Diffusion ◽  
General Protein

scholarly journals Septin-dependent compartmentalization of the endoplasmic reticulum during yeast polarized growth

2005 ◽  
Vol 169 (6) ◽  
pp. 897-908 ◽  
Author(s):  
Cosima Luedeke ◽  
Stéphanie Buvelot Frei ◽  
Ivo Sbalzarini ◽  
Heinz Schwarz ◽  
Anne Spang ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Plasma Membrane ◽  
Membrane Proteins ◽  
Diffusion Barriers ◽  
Yeast Cells ◽  
Dependent Manner ◽  
Protein Diffusion ◽  
Ultrastructural Studies ◽  
Bud Neck ◽  
Er Membrane

Polarized cells frequently use diffusion barriers to separate plasma membrane domains. It is unknown whether diffusion barriers also compartmentalize intracellular organelles. We used photobleaching techniques to characterize protein diffusion in the yeast endoplasmic reticulum (ER). Although a soluble protein diffused rapidly throughout the ER lumen, diffusion of ER membrane proteins was restricted at the bud neck. Ultrastructural studies and fluorescence microscopy revealed the presence of a ring of smooth ER at the bud neck. This ER domain and the restriction of diffusion for ER membrane proteins through the bud neck depended on septin function. The membrane-associated protein Bud6 localized to the bud neck in a septin-dependent manner and was required to restrict the diffusion of ER membrane proteins. Our results indicate that Bud6 acts downstream of septins to assemble a fence in the ER membrane at the bud neck. Thus, in polarized yeast cells, diffusion barriers compartmentalize the ER and the plasma membrane along parallel lines.

PROTEIN DIFFUSION BARRIERS IN THE ANTERIOR UVEA OF THE RABBIT EYE

2009 ◽  
Vol 53 (1) ◽  
pp. 67-76 ◽  
Author(s):  
OLAV ØYVIND PEDERSEN ◽  
ASBJØRN M. TØNJUM
Keyword(s):  
Diffusion Barriers ◽  
Protein Diffusion ◽  
Rabbit Eye ◽  
Anterior Uvea

scholarly journals Spatiotemporal Stop-and-go Dynamics of the Mitochondrial TOM Core Complex Correlates With Three-state Channel Activity

2021 ◽  
Author(s):  
Shuo Wang ◽  
Lukas Findeisen ◽  
Sebastian Leptihn ◽  
Mark Wallace ◽  
Marcel Hörning ◽  
...  
Keyword(s):  
Single Molecule ◽  
Protein Import ◽  
Protein Diffusion ◽  
Channel Activity ◽  
State Dependent ◽  
Stop And Go ◽  
Single Molecule Studies ◽  
General Protein ◽  
Opening And Closing ◽  
Permeability State

Abstract Single-molecule studies can reveal phenomena that remain hidden in ensemble measurements. Here, we show the correlation between lateral protein diffusion and channel activity of the general protein import pore of mitochondria (TOM-CC) in membranes resting on ultrathin hydrogel films. Using electrode-free optical recordings of ion flux, we find that TOM-CC switches reversibly between three states of ion permeability associated with protein diffusion. Freely diffusing TOM-CC molecules are observed in a high permeability state, while non-moving molecules are in an intermediate and a low permeability state. We explain this behavior by the mechanical binding of the two protruding Tom22 subunits to the hydrogel and a concomitant combinatorial opening and closing of the two β-barrel pores of TOM-CC. TOM-CC could thus be the first β-barrel protein channel to exhibit membrane state-dependent mechanosensitive properties.

scholarly journals Correlation of mitochondrial TOM core complex stop-and-go and open-closed channel dynamics

2021 ◽  
Author(s):  
Shuo Wang ◽  
Lukas Findeisen ◽  
Sebastian Leptihn ◽  
Mark I Wallace ◽  
Marcel Hörning ◽  
...  
Keyword(s):  
Protein Import ◽  
Mitochondrial Protein ◽  
Lateral Diffusion ◽  
Protein Diffusion ◽  
Channel Dynamics ◽  
Stop And Go ◽  
General Protein ◽  
Opening And Closing ◽  
The Relationship

The role of lateral diffusion of proteins in the membrane in the context of function has not been examined extensively. Here, we explore the relationship between protein lateral diffusion and channel activity of the general protein import pore of mitochondria (TOM-CC). Optical ion flux sensing through single TOM-CC molecules shows that TOM-CC can occupy three ion permeability states. Whereas freely diffusing TOM-CC molecules are preferentially found in a high permeability state, physical tethering to an agarose support causes the channels to transition to intermediate and low permeability states. This data shows that combinatorial opening and closing of the two pores of TOM-CC correlates with lateral protein diffusion in the membrane plane, and that the complex has mechanosensitive-like properties. This is the first demonstration of β-barrel protein mechanosensitivity, and has direct conceptual consequences for the understanding of the process of mitochondrial protein import. Our approach provides a novel tool to simultaneously study the interplay of membrane protein diffusion and channel dynamics.

Effect of piperacillin on morphology and viability of gram-negative bacteria

1984 ◽  
Vol 42 ◽  
pp. 218-219
Author(s):  
R. H. Liss
Keyword(s):  
Inhibitory Concentration ◽  
Cytoplasmic Membrane ◽  
Drug Binding ◽  
Gram Negative Bacteria ◽  
Bacterial Cells ◽  
Drug Induced ◽  
Penicillin Binding Proteins ◽  
Lactam Antibiotic ◽  
Drug Free ◽  
Tube Dilution

Piperacillip (PIP) is b-[D(-)-α-(4-ethy1-2,3-dioxo-l-piperzinylcar-bonylamino)-α-phenylacetamido]-penicillanate. The broad spectrum semisynthetic β-lactam antibiotic is believed to effect bactericidal activity through its affinity for penicillin-binding proteins (PBPs), enzymes on the bacterial cytoplasmic membrane that control elongation and septation during cell growth and division. The purpose of this study was to correlate penetration and binding of 14C-PIP in bacterial cells with drug-induced lethal changes assessed by microscopic, microbiologic and biochemical methods.The bacteria used were clinical isolates of Escherichia coli and Pseudomonas aeruginosa (Figure 1). Sensitivity to the drug was determined by serial tube dilution in Trypticase Soy Broth (BBL) at an inoculum of 104 organisms/ml; the minimum inhibitory concentration of piperacillin for both bacteria was 1 μg/ml. To assess drug binding to PBPs, the bacteria were incubated with 14C-PIP (5 μg/0.09 μCi/ml); controls, in drug-free medium.

Stress Relaxation and the Formation of Silicides in the Process of the Crystallization of NI-NB Films on SI

1991 ◽  
Vol 49 ◽  
pp. 898-899
Author(s):  
N. Rozhanski ◽  
V. Lifshitz
Keyword(s):  
Thin Films ◽  
Stress Relaxation ◽  
Integrated Circuits ◽  
Direct Evidence ◽  
Alloy Film ◽  
Diffusion Barriers ◽  
Effective Barrier

Thin films of amorphous Ni-Nb alloys are of interest since they can be used as diffusion barriers for integrated circuits on Si. A native SiO2 layer is an effective barrier for Ni diffusion but it deformation during the crystallization of the alloy film lead to the appearence of diffusion fluxes through it and the following formation of silicides. This study concerns the direct evidence of the action of stresses in the process of the crystallization of Ni-Nb films on Si and the structure of forming NiSi2 islands.

What do nanometer molecular trajectories tell us about heterogeneous cell surface domaines?

1995 ◽  
Vol 53 ◽  
pp. 786-787
Author(s):  
Watt W. Webb
Keyword(s):  
Cell Surface ◽  
Lipid Membranes ◽  
Surface Proteins ◽  
Protein Diffusion ◽  
Coated Pits ◽  
Cell Surface Proteins ◽  
Membrane Heterogeneity ◽  
Fluorescence Photobleaching Recovery ◽  
Photobleaching Recovery ◽  
Plasma Membrane Heterogeneity

Plasma membrane heterogeneity is implicit in the existence of specialized cell surface organelles which are necessary for cellular function; coated pits, post and pre-synaptic terminals, microvillae, caveolae, tight junctions, focal contacts and endothelial polarization are examples. The persistence of these discrete molecular aggregates depends on localized restraint of the constituent molecules within specific domaines in the cell surface by strong intermolecular bonds and/or anchorage to extended cytoskeleton. The observed plasticity of many of organelles and the dynamical modulation of domaines induced by cellular signaling evidence evanescent intermolecular interactions even in conspicuous aggregates. There is also strong evidence that universal restraints on the mobility of cell surface proteins persist virtually everywhere in cell surfaces, not only in the discrete organelles. Diffusion of cell surface proteins is slowed by several orders of magnitude relative to corresponding protein diffusion coefficients in isolated lipid membranes as has been determined by various ensemble average methods of measurement such as fluorescence photobleaching recovery(FPR).

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