In the following, the names of experimental collaborators are italicized

Mechanochemical self-organization in cells

We are interested in the emergent dynamics observed in animal cells, resulting from the coupling of active mechanics and biochemical signaling. We have theoretically shown that the coupling of non-linear signaling circuits and hydrodynamic interactions robustly leads to localized (i.e. spatially confined) dynamics in the actomyosin cortex. Experimental tests of this and further self-organized dynamics is currently performed by our collaborators. [In figure, emergent localized turbulence of actomyosin (pink) and Rho-A (gray). Y-axis = density, X-axis = space]

With Daniel Riveline, Olivier Pertz, Damian Brunner and Karsten Kruse

Localized states in active fluids (2022)

Curvature-dependent forces in DNA condensates

In viruses and cells, DNA is closely packed and tightly curved thanks to polyvalent cations inducing an effective attraction between its negatively charged filaments. Our understanding of this effective attraction remains very incomplete, mainly because it results from multiple microscopic mechanisms that are hard to predict starting from first principles. We study this fundamental attraction by combining structural data of DNA condensates realized in vitro with effective equilibrium theories, where inter-helical forces compete with DNA elasticity. [Figure is adapted from Barberi et al, Nucleic Acids Research (2021)]

With Amélie Leforestier, Françoise Livolant and Martin Lenz

Twist-induced local curvature of filaments in DNA toroids (2021)
Local structure of DNA toroids reveals curvature-dependent intermolecular forces (2021)

Protein-stabilized helical membrane tubes

ESCRT-III polymers are responsible for membrane remodeling in many cellular processes, ranging from the maturation of retroviruses (like HIV and Ebola) to the constriction of the cytokinetic bridge. Despite its ubiquitous biological role, many aspects of ESCRT-mediated membrane remodeling are still unclear. Recent in vitro experiments revealed that ESCRT polymers can reshape spherical vesicles into helical tubes. Inspired by structural insights from such experiments, we develop generic theories on the competition between ESCRT and membrane elasticity to shed light on the ESCRT-membrane interactions responsible of membrane remodeling in vivo. [Left panel from Moser Von Filseck et al, Nature Communications (2020). Right panel from my PhD thesis.]

With Joachim Moser Von Filseck, Aurélien Roux and Martin Lenz

Anisotropic ESCRT-III architecture governs helical membrane tube formation (2020)