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Large changes in cytoplasmic biopolymer concentration with osmolality indicate that macromolecular crowding may regulate protein–DNA interactions and growth rate in osmotically stressed Escherichia coli K‐12
Author(s) -
Cayley Scott,
Record M. Thomas
Publication year - 2004
Publication title -
journal of molecular recognition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.401
H-Index - 79
eISSN - 1099-1352
pISSN - 0952-3499
DOI - 10.1002/jmr.695
Subject(s) - cytoplasm , osmoprotectant , macromolecular crowding , osmotic concentration , biopolymer , growth rate , biochemistry , escherichia coli , nucleic acid , osmolyte , osmotic pressure , osmotic shock , betaine , chemistry , macromolecule , biophysics , biology , amino acid , polymer , geometry , mathematics , organic chemistry , gene , proline
From determination of amounts and concentrations of biopolymers and solutes in the cytoplasm of Escherichia coli , we are obtaining information needed to assess the effect of macromolecular crowding on cytoplasmic properties and processes of osmotically stressed bacteria. We observe that growth rate, and the amount of cytoplasmic water decrease and cytoplasmic concentrations of biopolymers and K + , increase with increasing osmolality, even for cells grown in the presence of osmoprotectants like glycine betaine. We observe general correlations between the amount of cytoplasmic water, growth rate and cytoplasmic K + concentration in osmotically stressed cells grown both with and without osmoprotectants. To explain these correlations, we propose that crowding increases with increasing growth osmolality, which in turn buffers the binding of proteins to nucleic acids against changes in cytoplasmic K + concentration and (by affecting biopolymer diffusion rates and/or assembly equilibria) is a determinant of growth rate of osmotically stressed cells. Changes in biopolymer concentration and crowding may also explain the increase of the activity coefficient of cytoplasmic water with increasing osmolality of growth in E. coli . Copyright © 2004 John Wiley & Sons, Ltd.