Quantifying surface tension and viscosity in biomolecular condensates by FRAP-ID.

Autor:	Santamaria A; Center for Structural Biology (CBS), CNRS, INSERM, Montpellier University, Montpellier, France., Hutin S; Laboratoire de Physiologie Cellulaire et Végétale, Université Grenoble-Alpes, CNRS, CEA, INRAE, IRIG-DBSCI, Grenoble, France., Doucet CM; Center for Structural Biology (CBS), CNRS, INSERM, Montpellier University, Montpellier, France., Zubieta C; Laboratoire de Physiologie Cellulaire et Végétale, Université Grenoble-Alpes, CNRS, CEA, INRAE, IRIG-DBSCI, Grenoble, France., Milhiet PE; Center for Structural Biology (CBS), CNRS, INSERM, Montpellier University, Montpellier, France., Costa L; Center for Structural Biology (CBS), CNRS, INSERM, Montpellier University, Montpellier, France. Electronic address: luca.costa@cnrs.fr.
Jazyk:	angličtina
Zdroj:	Biophysical journal [Biophys J] 2024 Oct 01; Vol. 123 (19), pp. 3366-3374. Date of Electronic Publication: 2024 Aug 08.
DOI:	10.1016/j.bpj.2024.07.043
Abstrakt:	Many proteins with intrinsically disordered regions undergo liquid-liquid phase separation under specific conditions in vitro and in vivo. These complex biopolymers form a metastable phase with distinct mechanical properties defining the timescale of their biological functions. However, determining these properties is nontrivial, even in vitro, and often requires multiple techniques. Here we report the measurement of both viscosity and surface tension of biomolecular condensates via correlative fluorescence microscopy and atomic force microscopy (AFM) in a single experiment (fluorescence recovery after probe-induced dewetting, FRAP-ID). Upon surface tension evaluation via regular AFM-force spectroscopy, controlled AFM indentations induce dry spots in fluorescent condensates on a glass coverslip. The subsequent rewetting exhibits a contact line velocity that is used to quantify the condensed-phase viscosity. Therefore, in contrast with fluorescence recovery after photobleaching (FRAP), where molecular diffusion is observed, in FRAP-ID fluorescence recovery is obtained through fluid rewetting and the subsequent morphological relaxation. We show that the latter can be used to cross-validate viscosity values determined during the rewetting regime. Making use of fluid mechanics, FRAP-ID is a valuable tool to evaluate the mechanical properties that govern the dynamics of biomolecular condensates and determine how these properties impact the temporal aspects of condensate functionality. Competing Interests: Declaration of interests The authors declare no competing interests. (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)
Databáze:	MEDLINE
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