Osmoprotection by carnitine in a Listeria monocytogenes mutant lacking the OpuC transporter: evidence for a low affinity carnitine uptake system

Katy Fraser, C. P. O'Byrne

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    A deletion mutant of Listeria monocytogenes lacking OpuC, an ABC transporter responsible for the uptake of the compatible solute carnitine, was constructed and carnitine transport assays confirmed that carnitine transport was defective in this mutant. However, the mutant retained the ability to derive osmoprotection from carnitine, suggesting the presence of a second uptake system for this compatible solute. Measurement of intracellular carnitine pools during balanced growth confirmed that the opuC mutant accumulated high levels of carnitine. These pools were only achieved in the mutant when high levels (1 mM) of carnitine were present extracellularly. When a lower level (100 muM) was supplied in the medium the mutant failed to accumulate a substantial intracellular pool and failed to derive osmoprotection from carnitine. These data suggest the presence of a second low affinity carnitine uptake system in this osmotolerant pathogen. (C) 2002 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.

    Original languageEnglish
    Pages (from-to)189-194
    Number of pages5
    JournalFEMS Microbiology Letters
    Issue number2
    Publication statusPublished - 2002


    • OpuC
    • carnitine
    • osmoprotection
    • compatible solute
    • Listeria monocytogenes
    • SCOTT-A
    • GROWTH
    • GENES

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