Macromolecular Crowding, Phase Separation, and Homeostasis in the Orchestration of Bacterial Cellular Functions

Abstract

Macromolecular crowding affects the activity of proteins and functional macromolecular complexes in all cells, including bacteria. Crowding, together with physicochemical parameters such as pH, ionic strength, and the energy status, influences the structure of the cytoplasm and thereby indirectly macromolecular function. Notably, crowding also promotes the formation of biomolecular condensates by phase separation, initially identified in eukaryotic cells but more recently discovered to play key functions in bacteria. Bacterial cells require a variety of mechanisms to maintain physicochemical homeostasis, in particular in environments with fluctuating conditions, and the formation of biomolecular condensates is emerging as one such mechanism. In this work, we connect physicochemical homeostasis and macromolecular crowding with the formation and function of biomolecular condensates in the bacterial cell and compare the supramolecular structures found in bacteria with those of eukaryotic cells. We focus on the effects of crowding and phase separation on the control of bacterial chromosome replication, segregation, and cell division, and we discuss the contribution of biomolecular condensates to bacterial cell fitness and adaptation to environmental stress. CONTENTS 1910 2.2.5. Fluidization of the Cytoplasm 1911 3. The Bacterial Nucleoid 1911 4. Crowding and Phase Separation in Membrane Environments 4.1. Remodeling of the Membrane by Crowding and Phase Separation 4.

Formation of vimentin biomolecular condensate-like structures under oxidative stress

“…Conversely, the process of phase separation is involved in the maintenance of cellular redox status (56). Additionally, macromolecular crowding-driven phase separation (57) can have important consequences in the rate, extent and pathways of protein oxidation (58). Therefore, a complex reciprocal modulation of phase separation and redox regulation can take place.…”

Introduction: Molecular Crowding

“…The ultimate goal of crowding studies remains to elucidate its impact on biological function. To this end, Monterroso et al analyzed how macromolecular crowding, phase separation, and physicochemical homeostasis orchestrate bacterial intracellular organization and essential cell-cycle processes. They first discussed the various factors influencing the structure of the cytoplasmincluding crowding and physicochemical parameters such as pH, ionic strength, and energy statusand compared the supramolecular structures found in bacteria with those of eukaryotic cells.…”