Single Particle Tracking Reveals Corralling of a Transmembrane Protein in a Double-Cushioned Lipid Bilayer Assembly

Langmuir ◽  
2011 ◽  
Vol 27 (1) ◽  
pp. 320-327 ◽  
Author(s):  
Kumud R. Poudel ◽  
David J. Keller ◽  
James A. Brozik
Keyword(s):  
Lipid Bilayer ◽  
Particle Tracking ◽  
Single Particle ◽  
Transmembrane Protein ◽  
Single Particle Tracking ◽  
Bilayer Assembly

scholarly journals Rapid diffusion of large TatA complexes detected using single particle tracking microscopy

2020 ◽  
Author(s):  
Aravindan Varadarajan ◽  
Felix Oswald ◽  
Holger Lill ◽  
Erwin J.G. Peterman ◽  
Yves J. M. Bollen
Keyword(s):  
Particle Tracking ◽  
Single Particle ◽  
Transmembrane Protein ◽  
Single Particle Tracking ◽  
Fast Diffusion ◽  
Translocation Event ◽  
Twin Arginine Translocation ◽  
Rhomboid Proteases ◽  
Folded Proteins ◽  
Membrane Spanning

AbstractThe twin-arginine translocation (Tat) system transports folded proteins across the cytoplasmic membrane of most bacteria and archaea. TatA, which contains a single membrane-spanning helix, is believed to be responsible for the actual translocation. According to the prevalent model, multiple TatA subunits form a transient protein-conducting pore, which disassembles after each translocation event. An alternative model exists, in which TatA proteins locally weaken the lipid bilayer to translocate folded proteins. Here, we imaged eGFP-fused TatA expressed from the genome in live E. coli cells. Images showed TatA occuring both in highly mobile monomers or small oligomers and in large, stable complexes that do not dissociate. Single-particle tracking revealed that large TatA complexes switch between fast and slow diffusion. The fast diffusion is too fast for a transmembrane protein complex consisting of multiple TatA monomers. In line with recent data on rhomboid proteases, we propose that TatA complexes switch between a slowly diffusing transmembrane conformation and a rapidly diffusing membrane-disrupting state that enables folded proteins to cross the membrane, in accordance with the membrane-weakening model.

Single Particle Tracking Analysis of the Chloroplast Division Protein FtsZ Anchoring to the Inner Envelope Membrane

2013 ◽  
Vol 19 (3) ◽  
pp. 507-512 ◽  
Author(s):  
Carol B. Johnson ◽  
Leung K. Tang ◽  
Aaron G. Smith ◽  
Akshaya Ravichandran ◽  
Zhiping Luo ◽  
...  
Keyword(s):  
Particle Tracking ◽  
Single Particle ◽  
Fluorescent Protein ◽  
Transmembrane Protein ◽  
Mean Square Displacement ◽  
Single Particle Tracking ◽  
Envelope Membrane ◽  
Plastid Division ◽  
Z Ring ◽  
Inner Envelope

AbstractReplication of chloroplast in plant cells is an essential process that requires co-assembly of the tubulin-like plastid division proteins FtsZ1 and FtsZ2 at mid-chloroplast to form a ring structure called the Z-ring. The Z-ring is stabilized via its interaction with the transmembrane protein ARC6 on the inner envelope membrane of chloroplasts. Plants lacking ARC6 are defective in plastid division and contain only one or two enlarged chloroplasts per cell with abnormal localization of FtsZ: instead of a single Z-ring, many short FtsZ filaments are distributed throughout the chloroplast. ARC6 is thought to be the anchoring point for FtsZ assemblies. To investigate the role of ARC6 in FtsZ anchoring, the mobility of green fluorescent protein–tagged FtsZ assemblies was assessed by single particle tracking in mutant plants lacking the ARC6 protein. Mean square displacement analysis showed that the mobility of FtsZ assemblies is to a large extent characterized by anomalous diffusion behavior (indicative of intermittent binding) and restricted diffusion suggesting that besides ARC6-mediated anchoring, an additional FtsZ-anchoring mechanism is present in chloroplasts.

scholarly journals Information-Efficient, Off-Center Sampling Results in Improved Precision in 3D Single-Particle Tracking Microscopy

Entropy ◽  
2021 ◽  
Vol 23 (5) ◽  
pp. 498
Author(s):  
Chen Zhang ◽  
Kevin Welsher
Keyword(s):  
Fisher Information ◽  
Particle Tracking ◽  
Single Particle ◽  
Biological Samples ◽  
Tracking System ◽  
Single Particle Tracking ◽  
Uniform Sampling ◽  
Single Dimension ◽  
3D Localization ◽  
Particle Localization

In this work, we present a 3D single-particle tracking system that can apply tailored sampling patterns to selectively extract photons that yield the most information for particle localization. We demonstrate that off-center sampling at locations predicted by Fisher information utilizes photons most efficiently. When performing localization in a single dimension, optimized off-center sampling patterns gave doubled precision compared to uniform sampling. A ~20% increase in precision compared to uniform sampling can be achieved when a similar off-center pattern is used in 3D localization. Here, we systematically investigated the photon efficiency of different emission patterns in a diffraction-limited system and achieved higher precision than uniform sampling. The ability to maximize information from the limited number of photons demonstrated here is critical for particle tracking applications in biological samples, where photons may be limited.

pH-Mediated nanoparticle dynamics in hydrogel nanocomposites

Soft Matter ◽  
2021 ◽  
Author(s):  
Katie A. Rose ◽  
Daeyeon Lee ◽  
Russell J. Composto
Keyword(s):  
Quantum Dot ◽  
Ethylene Glycol ◽  
Particle Tracking ◽  
Single Particle ◽  
Silica Particles ◽  
Single Particle Tracking ◽  
Poly Ethylene Glycol ◽  
Hydrogel Nanocomposites ◽  
Poly Ethylene ◽  
Nanoparticle Dynamics

The effect of static silica particles on the dynamics of quantum dot (QD) nanoparticles grafted with a poly(ethylene glycol) (PEG) brush in hydrogel nanocomposites is investigated using single particle tracking (SPT).

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