The regulation of glycine betaine accumulation has been investigated in Salmonella typhimurium. The size of the glycine betaine pool in the cells is determined by the external osmotic pressure and is largely independent of the external glycine betaine concentration. Analysis of the activity of the ProP and ProU transport systems suggests that other systems must be active in the regulation of the glycine betaine pool. Addition of p-chloromercuribenzoate (PCMB) or p-chloromercuribenzene sulphonate (PCMBS) to cells that have accumulated glycine betaine provokes rapid loss of glycine betaine. The route of glycine betaine efflux under the influence of PCMB is independent of either the ProP or ProU transport systems. Rapid loss of the accumulated pool of glycine betaine in the presence of PCMB is specific to glycine betaine and proline; accumulated pools of serine and lysine are not significantly affected by the –SH reagent. A specific glycine betaine/proline efflux system is postulated on the basis of these data and its role in the regulation of glycine betaine and proline accumulation is discussed.
BarkerE. P.,
BoothI. R.,
DinnbierU.,
EpsteinW.,
GajewskaA.1987; Evidence for multiple potassium export systems in Escherichia coli. Journal of Bacteriology 169:3743–3749
BoothI. R.,
HamiltonW. A.1980; Quantitative analysis of proton-linked transport system: β-galactoside exit in Escherichia coli. Biochemical Journal 188:467–473
CairneyJ.,
BoothI. R.,
HigginsC. F.1985a; Salmonella typhimurium proP gene encodes a transport system for the osmo- protectant glycine betaine. Journal of Bacteriology 164:1218–1223
CairneyJ.,
BoothI. R.,
HigginsC. F.1985b; Osmoregulation of gene expression in Salmonella typhimurium: proU encodes an osmotically-induced glycine betaine transport system. Journal of Bacteriology 164:1224–1232
CsonkaL. N.1982; A third L-proline permease in Salmonella typhimurium which functions in media of elevated osmotic strength. Journal of Bacteriology 151:1433–1443
CsonkaL. N.1988; Regulation of cytoplasmic proline levels in Salmonella typhimurium: effect of osmotic stresses on synthesis, degradation and cellular retention of proline. Journal of Bacteriology 170:2374–2378
DinnbierU.,
LimpinselE.,
SchmidR.,
BakkerE. P.1988; Transient accumulation of potassium glutamate and its replacement by trehalose during adaptation of growing cells of Escherichia coli K12 to elevated sodium chloride concentrations. Archives of Microbiology 150:348–357
DriessenA. J. M.,
KoningsW. N.1990; Reactive exofacial sulphydryl groups on the arginine–ornithine antiporter of Lactococcus lactis. Biochimica et Biophysica Acta 1015:87–95
FaatzE.,
MiddendorfA.,
BremerE.1988; Cloned structural genes for the osmotically regulated binding-protein-dependent glycine betaine transport system (ProU) of Escherichia coli K-12. Molecular Microbiology 2:265–279
LarsonP. L.,
SydnesL. K.,
LandfaldB.,
StromA. R.1987; Osmoregulation in Escherichia coli by accumulation of organic osmolytes: betaines, glutamic acid and trehalose. Archives of Microbiology 147:1–7
MilnerJ. L.,
GrotheS.,
WoodJ. M.1988; Proline porter II is activated by a hyperosmotic shift in both whole cells and membrane vesicles of Escherichia coli K.12. Journal of Biological Chemistry 263:14900–14905
RiouN.,
Le RudulierD.1990; Osmoregulation in Azospirillum brasilense: glycine betaine transport enhances growth and nitrogen fixation under salt stress. Journal of General Microbiology 136:1455–1461
RothW. G.,
LeckieM. P.,
DietzlerD. N.1984; Osmotic stress drastically inhibits active transport of carbohydrates by Escherichia coli. Biochemical and Biophysical Research Communications 126:442–449
StirlingD. A.,
HultonC. S. J.,
WaddellL.,
ParkS. F.,
StewartG. S. A. B.,
BoothI. R.,
HigginsC. F.1989; Molecular characterisation of the proU loci of Salmonella typhimurium and Escherichia coli: the osmoregulated glycine betaine transport systems. Molecular Microbiology 3:1025–1038
StyrvoldO. B.,
StromA. R.1991; Synthesis, accumulation, and excretion of trehalose in osmotically-stressed Escherichia coli K-12 strains: influence of amber suppressors and function of the periplasmic trehalase. Journal of Bacteriology 173:1187–1192