Evidence for the existence of a novel component of biological water stress (anhydrotic stress) inEscherichia coli

UmaPrasad, Gogineni; Gowrishankar, J.

doi:10.1007/bf02933035

Cited by 1 publication

(1 citation statement)

References 57 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The fact that glycerol, which freely equilibrates across the proteoliposomal membrane, did not lead to a similar response of BetP indicates that a symmetric increase of the concentration of a neutral solute on both sides of the liposomal membrane does not affect betaine transport. Consequently, anhydrotic stress does not seem to play a role for reconstituted BetP (37).…”

Section: Discussionmentioning

confidence: 89%

Osmosensor and Osmoregulator Properties of the Betaine Carrier BetP from Corynebacterium glutamicum in Proteoliposomes

Rübenhagen¹,

Rönsch²,

Jung³

et al. 2000

Journal of Biological Chemistry

120

189

View full text Add to dashboard Cite

The secondary glycine betaine uptake system BetP of Corynebacterium glutamicum was purified from Escherichia coli membranes in strep-tagged form after heterologous expression of the betP gene and was reconstituted in E. coli lipids. BetP retained its kinetic properties (V max and K m for betaine and Na ؉ ) as compared with intact cells. The influence of driving forces (Na ؉ gradient and/or electrical potential) on betaine uptake was quantified in proteoliposomes. BetP was effectively regulated by the external osmolality and was stimulated by the local anesthetic tetracaine. A shift of the optimum of osmotic stimulation to higher osmolalities was linearly correlated with an increasing share of phosphatidyl glycerol, the major lipid of the C. glutamicum plasma membrane in the E. coli lipid proteoliposomes. This finding correlates with results demonstrating an identical shift when betP was expressed in E. coli instead of C. glutamicum. These data indicate that (i) BetP comprises all elements of osmosensing and osmoregulatory mechanisms of betaine uptake, (ii) osmoregulation of BetP is directly related to protein/membrane interactions, (iii) the turgor pressure presumably plays no major role in osmoregulation of BetP, and (iv) the regulatory properties of BetP may be related to the physical state of the surrounding membrane.

show abstract

Section: Discussionmentioning

confidence: 89%