UMR 8640 : Biophysical chemistry

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Programmed Self-Assembly of a Biochemical and Magnetic Scaffold to Trigger and Manipulate Microtubule Structures

Scientific REPOrtS | 7: 11344 | 2017

 

Artificial bio-based scaffolds offer broad applications in bioinspired chemistry, nanomedicine, and material science. One current challenge is to understand how the programmed self-assembly of biomolecules at the nanometre level can dictate the emergence of new functional properties at the mesoscopic scale. Here we report a general approach to design genetically encoded protein-based scaffolds with modular biochemical and magnetic functions. By combining chemically induced dimerization strategies and biomineralisation, we engineered ferritin nanocages to nucleate and manipulate microtubule structures upon magnetic actuation. Triggering the self-assembly of engineered ferritins into micrometric scaffolds mimics the function of centrosomes, the microtubule organizing centres of cells, and provides unique magnetic and self-organizing properties. We anticipate that our approach could be transposed to control various biological processes and extend to broader applications in biotechnology or material chemistry.

Dynamic multicolor protein labeling in living cells

Chem. Sci.2017, Advance Article 

 

Yellow Fluorescence-Activating and absorption-Shifting Tag (Y-FAST, hereafter called FAST) is a 14-kDa protein tag giving a bright green-yellow fluorescent complex upon interaction with the fluorogenic dye 4-hydroxy-3-methylbenzylidene rhodanine (HMBR). Here, we report a collection of fluorogens enabling to tune the fluorescence color of FAST from greenyellow to orange and red. Beyond allowing multicolor imaging of FAST-tagged proteins in live cells, these fluorogens enable dynamic color switching because of FAST’s reversible labeling. This unprecedented behavior allows selective detection of FAST-tagged proteins in cells expressing both green and red fluorescent species through two-color crosscorrelation, opening exciting prospects to overcome spectral crowding and push the frontiers of multiplexed imaging.

Interview Arnaud GAUTIER, a chemical biologist !

Arnaud GAUTIER, Maître de Conférence au sein du Département de Chimie de l'École normale supérieure est lauréat du financement ERC Consolidator Grant 2016 et Médaille de Bronze du CNRS.

 

Visionnez son interview où il nous explique ce qu'est la chémobiologie et nous détaille ses projets à venir !

Temperature-Switchable Control of Ligand Display on Adlayers of Mixed Poly(lysine)‑g‑(PEO) and Poly(lysine)‑g‑(ligand-modified poly‑N‑isopropylacrylamide)

Biomacromolecules2016 May 9;17(5):1727-36

 

Adlayers of poly(lysine)-g -PEG comblike copolymer are extensively used to prepare cell-repellant and proteinrepellent surfaces by a straightforward coulomb-driven adsorption that is compatible with diverse substrates (glass, Petri dish, etc.). To endow surfaces with functional properties, namely, controlled ligand-protein binding, comblike poly(lysine) derivatives were used to deposit temperature-responsive poly(NIPAM) macrografts mixed with PEG ones on glass surfaces. Simple surface immersion in mixed solutions of biotin-modifi ed poly(lysine)-g -poly(N -isopropylacrylamide) and poly(lysine)-g -poly(ethylene oxide) yielded robust adlayers whose composition refl ected the ratio between the two polymers in solution. We show by fluorescence imaging, and comparison with repellent 100% PEGylated patterns, that specifi c binding of model avidin/particle conjugates (diameters of ca. 10 or 200 nm) was controlled by temperature switch. The biotin ligand was displayed and accessible at low T , or hidden at T  > LCST. Topography and mechanical mapping measurements by AFM confi rmed the swelling/collapse status of PNIPAM macrografts in the adlayer at low/high T , respectively. Temperature-responsive comblike PLL derivative that can spontaneously cover anionic interfaces is a promising platform enabling good control on the deposition and accessibility of biofunctional groups on various solid surfaces

Long-term in vivo single-cell lineage tracing of deep structures using three-photon activation

Light: Science & Applications (2016) 5, e16084

 

Genetic labeling techniques allow for noninvasive lineage tracing of cells in vivo. Two-photon inducible activators provide spatial resolution for superficial cells, but labeling cells located deep within tissues is precluded by scattering of the far-red illumination required for two-photon photolysis. Three-photon illumination has been shown to overcome the limitations of two-photon microscopy for in vivo imaging of deep structures, but whether it can be used for photoactivation remains to be tested. Here we show, both theoretically and experimentally, that three-photon illumination overcomes scattering problems by combining longer wavelength excitation with high uncaging three-photon cross-section molecules. We prospectively labeled heart muscle cells in zebrafish embryos and found permanent labeling in their progeny in adult animals with negligible tissue damage. This technique allows for a noninvasive genetic manipulation in vivo with spatial, temporal and cell-type specificity, and may have wide applicability in experimental biology.