Laboratoire P.A.S.T.E.U.R

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Actin-Network Architecture Regulates Microtubule Dynamics

Curr Biol. (16) 2018 : 2647-2656

 

In Brief Colin et al. show that branched actin networks block microtubule growth and trigger microtubule disassembly using Xenopus egg extracts and in vitro reconstituted systems. This demonstrates the role of actin-network architecture in regulating microtubule dynamics. 

 

Highlights 

·     Branched actin networks block microtubule growth and trigger their disassembly 

·     Unbranched actin networks do not interfere with microtubule growth 

·     Branched actin networks perturb meiotic spindle assembly in Xenopusegg extracts

 

Circularly permuted fluorogenic proteins for the design of modular biosensors

ACS Chem. Biol. 2018

Fluorescent reporters are essential components for the design of optical biosensors able to image intracellular analytes in living cells. Herein, we describe the development of circularly permuted variants of Fluorescence-Activating and absorption-Shifting Tag (FAST) and demonstrate their potential as reporting module in biosensors. Circularly permutated FAST (cpFAST) variants allow one to condition the binding and activation of a fluorogenic ligand (and thus fluorescence) to analyte recognition by coupling them with analyte-binding domains. We demonstrated their use for biosensor design by generating multicolor plug-and-play fluorogenic biosensors for imaging the intracellular levels of Ca2+in living mammalian cells in real-time.

Taming Nickel-Catalyzed Suzuki-Miyaura Coupling: A Mechanistic Focus on Boron-to-Nickel Transmetalation

ACS Catal. 2018, 8, 4812−4823

 

The mechanism of boron-to-nickel transmetalation, the key step of the nickel-catalyzed Suzuki-Miyaura (SM) coupling, was examined both experimentally and theoretically. Dinuclear μ -hydroxo-bridged complexes formed by reaction of trans[ArNi(PR3)2X] with hydroxide are not directly involved in transmetalation, but they rather act as a resting state for the catalyst. The base/boronic acid ratio is the crucial parameter, as it modulates the extent of formation of these dinuclear species and thus tunes the catalytic activity. These findings explain some limitations encountered in practical applications of nickel-catalyzed S-M couplings and suggest how to tailor the experimental conditions in order to overcome these difficulties.

Fluorogenic Probing of Membrane Protein Trafficking

Bioconjugate Chem. 2018

 

Methods to differentially label cell-surface and intracellular membrane proteins are indispensable for understanding their function and the regulation of their trafficking. We present an effi cient strategy for the rapid and selective fluorescent labeling of membrane proteins based on the chemical-genetic fl uorescent marker FAST (fluorescence activating and absorption-shifting tag). Cell-surface FASTtagged proteins could be selectively and rapidly labeled using fluorogenic membrane-impermeant 4-hydroxybenzylidene rhodanine (HBR) analogs. This approach allows the study of protein trafficking at the plasma membrane with various fluorometric techniques, and opens exciting prospects for the high-throughput screening of small molecules able to restore disease-related trafficking defects.

A novel diarylethene-based photoswitchable chelator for reversible release and capture of Ca2+ in aqueous media

Nadia Dozova,Guillaume Pousse, Bogdan Barnych, Jean-Maurice Mallet, Janine Cossy, Bernard Valeur, Pascal Plaza

 

DOI:10.1016/j.jphotochem.2018.04.029

 

A photochromic calcium chelator is reported to reversibly reduce its affinity for calcium upon photoswitching in aqueous media.