This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Mendum, M. L. Articles by Smith, L. T. Search for Related Content PubMed PubMed Citation Articles by Mendum, M. L. Articles by Smith, L. T. Agricola Articles by Mendum, M. L. Articles by Smith, L. T.

Gbu Glycine Betaine Porter and Carnitine Uptake in Osmotically Stressed Listeria monocytogenes Cells

Department of Agronomy and Range Science, University of California, Davis, California 95616

Received 6 March 2002/ Accepted 24 August 2002

The food-borne pathogen Listeria monocytogenes grows actively under high-salt conditions by accumulating compatible solutes such as glycine betaine and carnitine from the medium. We report here that the dominant transport system for glycine betaine uptake, the Gbu porter, may act as a secondary uptake system for carnitine, with a K_m of 4 mM for carnitine uptake and measurable uptake at carnitine concentrations as low as 10 µM. This porter has a K_m for glycine betaine uptake of about 6 µM. The dedicated carnitine porter, OpuC, has a K_m for carnitine uptake of 1 to 3 µM and a V_max of approximately 15 nmol/min/mg of protein. Mutants lacking either opuC or gbu were used to study the effects of four carnitine analogs on growth and uptake of osmolytes. In strain DP-L1044, which had OpuC and the two glycine betaine porters Gbu and BetL, triethylglycine was most effective in inhibiting growth in the presence of glycine betaine, but trigonelline was best at inhibiting growth in the presence of carnitine. Carnitine uptake through OpuC was inhibited by -butyrobetaine. Dimethylglycine inhibited both glycine betaine and carnitine uptake through the Gbu porter. Carnitine uptake through the Gbu porter was inhibited by triethylglycine. Glycine betaine uptake through the BetL porter was strongly inhibited by trigonelline and triethylglycine. These results suggest that it is possible to reduce the growth of L. monocytogenes under osmotically stressful conditions by inhibiting glycine betaine and carnitine uptake but that to do so, multiple uptake systems must be affected.

This article has been cited by other articles:

• Ozcan, N., Ejsing, C. S., Shevchenko, A., Lipski, A., Morbach, S., Kramer, R. (2007). Osmolality, Temperature, and Membrane Lipid Composition Modulate the Activity of Betaine Transporter BetP in Corynebacterium glutamicum. J. Bacteriol. 189: 7485-7496 [Abstract] [Full Text]  
• Angelidis, A. S., Smith, G. M. (2003). Three Transporters Mediate Uptake of Glycine Betaine and Carnitine by Listeria monocytogenes in Response to Hyperosmotic Stress. Appl. Environ. Microbiol. 69: 1013-1022 [Abstract] [Full Text]