Transport of glycine-betaine by Listeria monocytogenes |
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Authors: | R A Patchett A F Kelly R G Kroll |
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Institution: | (1) Institute of Food Research, Earley Gate, Whiteknights Road, KG6 2EF Reading, UK;(2) Present address: Torry Research Station, MAFF, 135 Abbey Road, AB9 8DG Aberdeen, UK |
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Abstract: | Uptake of 14C]glycine-betaine by Listeria monocytogenes was stimulated by NaCl with optimal stimulation at 0.4–0.5 M. The glycine-betaine transport system had a K
m of 22 M and a V
max of 11.7 nmol-1 min-1 mg-1 protein when grown in the absence of NaCl. When grown in the presence of 0.8 M NaCl the V
max increased to 27.0 nmol-1 min-1 mg-1 protein in 0.8 M NaCl. At NaCl concentrations above 0.5 M the uptake rate of glycine-betaine was reduced. Measurement of intracellular K+ concentrations and fluorescent dye quenching indicated that higher NaCl concentrations also led to a decrease in the electrochemical potential difference across the cytoplasmic membrane. Uptake of glycine was also observed, but this was not stimulated by NaCl. |
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Keywords: | Listeria monocytogenes Glycine-betaine Osmoprotectants Transport |
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