scholarly journals 1H0900 Regulation mechanism for the movement of transmembrane proteins and phospholipids : An approach by single molecule techniques

2002 ◽  
Vol 42 (supplement2) ◽  
pp. S41
Author(s):  
K. Murase ◽  
Y. Hirako ◽  
T. Fujiwara ◽  
R. Iino ◽  
K. Owaribe ◽  
...  
2011 ◽  
Vol 51 (supplement) ◽  
pp. S93-S94
Author(s):  
Koichiro M. Hirosawa ◽  
Kenta J. Yoshida ◽  
Kenichi G. N. Suzuki ◽  
Takahiro K. Fujiwara ◽  
Ankita Chadda ◽  
...  

2020 ◽  
Author(s):  
Jaap van Krugten ◽  
Noémie Danné ◽  
Erwin J.G. Peterman

AbstractSensing and reacting to the environment is essential for survival and procreation of most organisms. Caenorhabditis elegans senses soluble chemicals with transmembrane proteins (TPs) in the cilia of its chemosensory neurons. Development, maintenance and function of these cilia relies on intraflagellar transport (IFT), in which motor proteins transport cargo, including sensory TPs, back and forth along the ciliary axoneme. Here we use live fluorescence imaging to show that IFT machinery and the sensory TP OCR-2 reversibly redistribute along the cilium after exposure to repellant chemicals. To elucidate the underlying mechanisms, we performed single-molecule tracking experiments and found that OCR-2 distribution depends on an intricate interplay between IFT-driven transport, normal diffusion and subdiffusion that depends on the specific location in the cilium. These insights in the role of IFT on the dynamics of cellular signal transduction contribute to a deeper understanding of the regulation of sensory TPs and chemosensing.


2021 ◽  
Author(s):  
Christin Fuks ◽  
Sebastian Falkner ◽  
Nadine Schwierz ◽  
Martin Hengesbach

ABSTRACTRiboswitch RNAs regulate gene expression by conformational changes induced by environmental conditions and specific ligand binding. The guanidine-II riboswitch is proposed to bind the small molecule guanidinium and to subsequently form a kissing loop interaction between the P1 and P2 hairpins. While an interaction was shown for isolated hairpins in crystallization and EPR experiments, an intrastrand kissing loop formation has not been demonstrated. Here, we report the first evidence of this interaction in cis in a ligand and Mg2+ dependent manner. Using single-molecule FRET spectroscopy and detailed structural information from coarse-grained simulations, we observe and characterize three interconvertible states representing an open and kissing loop conformation as well as a novel Mg2+ dependent state for the guanidine-II riboswitch from E. coli. The results further substantiate the proposed switching mechanism and provide detailed insight into the regulation mechanism for the guanidine-II riboswitch class. Combining single molecule experiments and coarse-grained simulations therefore provides a promising perspective in resolving the conformational changes induced by environmental conditions and to yield molecular insights into RNA regulation.


2020 ◽  
Author(s):  
Pedro M. Pereira ◽  
Nils Gustafsson ◽  
Mark Marsh ◽  
Musa M. Mhlanga ◽  
Ricardo Henriques

Localization based super-resolution microscopy relies on the detection of individual molecules cycling between fluorescent and non-fluorescent states. These transitions are commonly regulated by high-intensity illumination, imposing constrains to imaging hardware and producing sample photodamage. Here, we propose single-molecule self-quenching as a mechanism to generate spontaneous photoswitching independent of illumination. To demonstrate this principle, we developed a new class of DNA-based open-source Super-Resolution probes named Super-Beacons, with photoswitching kinetics that can be tuned structurally, thermally and chemically. The potential of these probes for live-cell friendly Super-Resolution Microscopy without high-illumination or toxic imaging buffers is revealed by imaging Interferon Inducible Transmembrane proteins (IFITMs) at sub-100nm resolutions.


2012 ◽  
Vol 2012 ◽  
pp. 1-9 ◽  
Author(s):  
Kai-Chun Chang

Programmed ribosomal frameshifting (PRF) serves as an intrinsic translational regulation mechanism employed by some viruses to control the ratio between structural and enzymatic proteins. Most viral mRNAs which use PRF adapt an H-type pseudoknot to stimulate −1 PRF. The relationship between the thermodynamic stability and the frameshifting efficiency of pseudoknots has not been fully understood. Recently, single-molecule force spectroscopy has revealed that the frequency of −1 PRF correlates with the unwinding forces required for disrupting pseudoknots, and that some of the unwinding work dissipates irreversibly due to the torsional restraint of pseudoknots. Complementary to single-molecule techniques, computational modeling provides insights into global motions of the ribosome, whose structural transitions during frameshifting have not yet been elucidated in atomic detail. Taken together, recent advances in biophysical tools may help to develop antiviral therapies that target the ubiquitous −1 PRF mechanism among viruses.


2002 ◽  
Vol 42 (supplement2) ◽  
pp. S135
Author(s):  
K. Murase ◽  
Y. Hirako ◽  
T. Fujiwara ◽  
R. Iino ◽  
K. Owaribe ◽  
...  

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