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Biol Open. 2019 Jul 10;8(7). pii: bio044529. doi: 10.1242/bio.044529.

Analysis of novel hyperosmotic shock response suggests 'beads in liquid' cytosol structure.

Author information

1
Federal Research Center "Fundamentals of Biotechnology" of the Russian Academy of Sciences, Bach Institute of Biochemistry, Leninsky Ave. 33, bld. 2, Moscow 119071, Russia alexvir@gmail.com agaphonov2013@hotmail.com.
2
A.N. Belozersky Institute of Physico-chemical Biology, M.V. Lomonosov Moscow State University, Leninskie gori 1, bldg 40, Moscow 119234, Russia.
3
Federal Research Center "Fundamentals of Biotechnology" of the Russian Academy of Sciences, Bach Institute of Biochemistry, Leninsky Ave. 33, bld. 2, Moscow 119071, Russia.
4
Chair of Molecular and Cell Biology, Moscow Institute of Physics and Technology (State University), Institutskiy per. 9, Dolgoprudny, Moscow Region 141701, Russia.
5
School of Biological and Medical Physics, Moscow Institute of Physics and Technology (State University), Institutskiy per. 9, Dolgoprudny, Moscow Region 141701, Russia.
6
Department of Biochemistry and Molecular Medicine, Faculty of Medicine, M.V. Lomonosov Moscow State University, Lomonosovskiy pr., 27 bldg 1, Moscow 119192, Russia.
7
V. I. Kulakov National Medical Research Center for Obstetrics, Gynecology, and Perinatology, Moscow 117198, Russia.
8
Faculty of Biology, M. V. Lomonosov Moscow State University, Moscow 119234, Russia.
9
Institute of Cell Biophysics of the Russian Academy of Sciences, Institutskaya str., 3, Moscow Region, 142290 Puschino, Russia.

Abstract

Proteins can aggregate in response to stresses, including hyperosmotic shock. Formation and disassembly of aggregates is a relatively slow process. We describe a novel instant response of the cell to hyperosmosis, during which chaperones and other proteins form numerous foci with properties uncharacteristic of classical aggregates. These foci appeared/disappeared seconds after shock onset/removal, in close correlation with cell volume changes. Genome-wide and targeted testing revealed chaperones, metabolic enzymes, P-body components and amyloidogenic proteins in the foci. Most of these proteins can form large assemblies and for some, the assembled state was pre-requisite for participation in foci. A genome-wide screen failed to identify genes whose absence prevented foci participation by Hsp70. Shapes of and interconnections between foci, revealed by super-resolution microscopy, indicated that the foci were compressed between other entities. Based on our findings, we suggest a new model of cytosol architecture as a collection of numerous gel-like regions suspended in a liquid network. This network is reduced in volume in response to hyperosmosis and forms small pockets between the gel-like regions.

KEYWORDS:

Aggregation; Amyloid; Chaperone; Cytoplasm; Foci; Hyperosmotic shock; Liquid–liquid phase separation; P-bodies; Yeast

Conflict of interest statement

Competing interestsThe authors declare no competing or financial interests.

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