Open AccessSodium-driven, osmotically activated glycine betaine transport in Listeria monocytogenes membrane vesicles
Author(s) -
P.N.M. Gerhardt,
Linda Tombras Smith,
Gary M. Smith
Publication year - 1996
Publication title -
journal of bacteriology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.652
H-Index - 246
eISSN - 1067-8832
pISSN - 0021-9193
DOI - 10.1128/jb.178.21.6105-6109.1996
Subject(s) - betaine , vesicle , glycine , sodium , osmotic concentration , biochemistry , osmotic pressure , osmotic shock , biology , osmoprotectant , biophysics , membrane transport , proline , membrane , chemistry , amino acid , organic chemistry , gene
Transport of the osmoprotectant and cryoprotectant glycine betaine was investigated in membrane vesicles of Listeria monocytogenes. Uptake-driving transmembrane potentials ranging from 111 to 122 mV within the pH range of 5.5 to 7.5 could be generated by the electron donor system ascorbate-phenazine methosulfate but not by the electron donor system ascorbate-N,N,N',N'-tetramethyl-p-phenylenediamine. Transport was dependent on both high concentrations of sodium ion and the presence of a hypertonic solute gradient. Arrhenius-type temperature activation was observed. Lineweaver-Burk plots indicated a Km of 4.4 microM for glycine betaine and a Vmax of 700 pmol/min x mg of protein. The Michaelis constant for NaCl depended on the solute used to maintain a constant hyperosmotic pressure, and the Km values were 200 and 75 mM when KCl and sucrose were employed, respectively. Transport was 65% lower in vesicles derived from cells grown under stress provided by KCI rather than NaCl and approximately 94% lower in vesicles derived from cells that were not grown under osmotic stress. This porter appears to be specific for glycine betaine, since neither proline, carnitine, nor choline inhibited uptake effectively. Kinetic studies using ionophores and artificial gradients indicate that glycine betaine is cotransported with sodium ion.