Faculty Opinions recommendation of Single-molecule motions and interactions in live cells reveal target search dynamics in mismatch repair.

2016 ◽  
Author(s):  
Martin Marinus
Keyword(s):  
Mismatch Repair ◽  
Single Molecule ◽  
Live Cells ◽  
Target Search

scholarly journals Single-molecule imaging reveals target-search mechanisms during DNA mismatch repair

2012 ◽  
Vol 109 (45) ◽  
pp. E3074-E3083 ◽  
Author(s):  
J. Gorman ◽  
F. Wang ◽  
S. Redding ◽  
A. J. Plys ◽  
T. Fazio ◽  
...  
Keyword(s):  
Mismatch Repair ◽  
Single Molecule ◽  
Dna Mismatch Repair ◽  
Single Molecule Imaging ◽  
Target Search ◽  
Dna Mismatch

scholarly journals Single-molecule motions and interactions in live cells reveal target search dynamics in mismatch repair

2015 ◽  
Vol 112 (50) ◽  
pp. E6898-E6906 ◽  
Author(s):  
Yi Liao ◽  
Jeremy W. Schroeder ◽  
Burke Gao ◽  
Lyle A. Simmons ◽  
Julie S. Biteen
Keyword(s):  
Mismatch Repair ◽  
Single Molecule ◽  
Nucleotide Binding ◽  
Separation Distance ◽  
Live Cells ◽  
Superresolution Microscopy ◽  
Replication Errors ◽  
Dynamic Movement ◽  
Dna Replication Errors

MutS is responsible for initiating the correction of DNA replication errors. To understand how MutS searches for and identifies rare base-pair mismatches, we characterized the dynamic movement of MutS and the replisome in real time using superresolution microscopy and single-molecule tracking in living cells. We report that MutS dynamics are heterogeneous in cells, with one MutS population exploring the nucleoid rapidly, while another MutS population moves to and transiently dwells at the replisome region, even in the absence of appreciable mismatch formation. Analysis of MutS motion shows that the speed of MutS is correlated with its separation distance from the replisome and that MutS motion slows when it enters the replisome region. We also show that mismatch detection increases MutS speed, supporting the model for MutS sliding clamp formation after mismatch recognition. Using variants of MutS and the replication processivity clamp to impair mismatch repair, we find that MutS dynamically moves to and from the replisome before mismatch binding to scan for errors. Furthermore, a block to DNA synthesis shows that MutS is only capable of binding mismatches near the replisome. It is well-established that MutS engages in an ATPase cycle, which is necessary for signaling downstream events. We show that a variant of MutS with a nucleotide binding defect is no longer capable of dynamic movement to and from the replisome, showing that proper nucleotide binding is critical for MutS to localize to the replisome in vivo. Our results provide mechanistic insight into the trafficking and movement of MutS in live cells as it searches for mismatches.

scholarly journals Single-molecule tracking in live cells reveals distinct target-search strategies of transcription factors in the nucleus

eLife ◽  
2014 ◽  
Vol 3 ◽  
Author(s):  
Ignacio Izeddin ◽  
Vincent Récamier ◽  
Lana Bosanac ◽  
Ibrahim I Cissé ◽  
Lydia Boudarene ◽  
...  
Keyword(s):  
Gene Regulation ◽  
Transcription Factors ◽  
Single Molecule ◽  
Nuclear Architecture ◽  
Elongation Factor ◽  
Live Cells ◽  
Dependent Manner ◽  
Target Search ◽  
Single Molecule Tracking ◽  
Nuclear Structures

Gene regulation relies on transcription factors (TFs) exploring the nucleus searching their targets. So far, most studies have focused on how fast TFs diffuse, underestimating the role of nuclear architecture. We implemented a single-molecule tracking assay to determine TFs dynamics. We found that c-Myc is a global explorer of the nucleus. In contrast, the positive transcription elongation factor P-TEFb is a local explorer that oversamples its environment. Consequently, each c-Myc molecule is equally available for all nuclear sites while P-TEFb reaches its targets in a position-dependent manner. Our observations are consistent with a model in which the exploration geometry of TFs is restrained by their interactions with nuclear structures and not by exclusion. The geometry-controlled kinetics of TFs target-search illustrates the influence of nuclear architecture on gene regulation, and has strong implications on how proteins react in the nucleus and how their function can be regulated in space and time.

scholarly journals Motional dynamics of single Patched1 molecules in cilia are controlled by Hedgehog and cholesterol

2019 ◽  
Vol 116 (12) ◽  
pp. 5550-5557 ◽  
Author(s):  
Lucien E. Weiss ◽  
Ljiljana Milenkovic ◽  
Joshua Yoon ◽  
Tim Stearns ◽  
W. E. Moerner
Keyword(s):  
Single Molecule ◽  
Hedgehog Signaling ◽  
Primary Cilia ◽  
Transmembrane Protein ◽  
Cellular Level ◽  
Live Cells ◽  
Cholesterol Depletion ◽  
Motional Dynamics ◽  
Directional Transport ◽  
Bulk Behavior

The Hedgehog-signaling pathway is an important target in cancer research and regenerative medicine; yet, on the cellular level, many steps are still poorly understood. Extensive studies of the bulk behavior of the key proteins in the pathway established that during signal transduction they dynamically localize in primary cilia, antenna-like solitary organelles present on most cells. The secreted Hedgehog ligand Sonic Hedgehog (SHH) binds to its receptor Patched1 (PTCH1) in primary cilia, causing its inactivation and delocalization from cilia. At the same time, the transmembrane protein Smoothened (SMO) is released of its inhibition by PTCH1 and accumulates in cilia. We used advanced, single molecule-based microscopy to investigate these processes in live cells. As previously observed for SMO, PTCH1 molecules in cilia predominantly move by diffusion and less frequently by directional transport, and spend a fraction of time confined. After treatment with SHH we observed two major changes in the motional dynamics of PTCH1 in cilia. First, PTCH1 molecules spend more time as confined, and less time freely diffusing. This result could be mimicked by a depletion of cholesterol from cells. Second, after treatment with SHH, but not after cholesterol depletion, the molecules that remain in the diffusive state showed a significant increase in the diffusion coefficient. Therefore, PTCH1 inactivation by SHH changes the diffusive motion of PTCH1, possibly by modifying the membrane microenvironment in which PTCH1 resides.

scholarly journals Phase-Separated Transcriptional Condensates Accelerate Target-Search Process Revealed by Live-Cell Single-Molecule Imaging

Cell Reports ◽  
2020 ◽  
Vol 33 (2) ◽  
pp. 108248 ◽  
Author(s):  
Samantha Kent ◽  
Kyle Brown ◽  
Chou-hsun Yang ◽  
Njood Alsaihati ◽  
Christina Tian ◽  
...  
Keyword(s):  
Single Molecule ◽  
Live Cell ◽  
Search Process ◽  
Single Molecule Imaging ◽  
Target Search

scholarly journals A Photoactivatable Push−Pull Fluorophore for Single-Molecule Imaging in Live Cells

2008 ◽  
Vol 130 (29) ◽  
pp. 9204-9205 ◽  
Author(s):  
Samuel J. Lord ◽  
Nicholas R. Conley ◽  
Hsiao-lu D. Lee ◽  
Reichel Samuel ◽  
Na Liu ◽  
...  
Keyword(s):  
Single Molecule ◽  
Live Cells ◽  
Single Molecule Imaging

scholarly journals Full characterization of GPCR monomer–dimer dynamic equilibrium by single molecule imaging

2011 ◽  
Vol 192 (3) ◽  
pp. 463-480 ◽  
Author(s):  
Rinshi S. Kasai ◽  
Kenichi G. N. Suzuki ◽  
Eric R. Prossnitz ◽  
Ikuko Koyama-Honda ◽  
Chieko Nakada ◽  
...  
Keyword(s):  
Equilibrium Constant ◽  
Single Molecule ◽  
Dynamic Equilibrium ◽  
Dissociation Rate ◽  
Formyl Peptide Receptor ◽  
Live Cells ◽  
Imaging Method ◽  
Full Characterization ◽  
Before And After ◽  
Dissociation Rate Constants

Receptor dimerization is important for many signaling pathways. However, the monomer–dimer equilibrium has never been fully characterized for any receptor with a 2D equilibrium constant as well as association/dissociation rate constants (termed super-quantification). Here, we determined the dynamic equilibrium for the N-formyl peptide receptor (FPR), a chemoattractant G protein–coupled receptor (GPCR), in live cells at 37°C by developing a single fluorescent-molecule imaging method. Both before and after liganding, the dimer–monomer 2D equilibrium is unchanged, giving an equilibrium constant of 3.6 copies/µm2, with a dissociation and 2D association rate constant of 11.0 s−1 and 3.1 copies/µm2s−1, respectively. At physiological expression levels of ∼2.1 receptor copies/µm2 (∼6,000 copies/cell), monomers continually convert into dimers every 150 ms, dimers dissociate into monomers in 91 ms, and at any moment, 2,500 and 3,500 receptor molecules participate in transient dimers and monomers, respectively. Not only do FPR dimers fall apart rapidly, but FPR monomers also convert into dimers very quickly.

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