Journal Article


C Hill
T Abee
C G Gahan
R D Sleator



molecular sequence data amino acid sequence mutation cloning molecular escherichia coli genes bacterial betl protein listeria monocytogenes listeria monocytogenes dna bacterial water electrolyte balance genetics metabolism sodium chloride betaine biological transport active dna primers base sequence genetic complementation test bacterial proteins kinetics carrier proteins

Identification and disruption of BetL, a secondary glycine betaine transport system linked to the salt tolerance of Listeria monocytogenes LO28. (1999)

Abstract The trimethylammonium compound glycine betaine (N,N, N-trimethylglycine) can be accumulated to high intracellular concentrations, conferring enhanced osmo- and cryotolerance upon Listeria monocytogenes. We report the identification of betL, a gene encoding a glycine betaine uptake system in L. monocytogenes, isolated by functional complementation of the betaine uptake mutant Escherichia coli MKH13. The betL gene is preceded by a consensus sigmaB-dependent promoter and is predicted to encode a 55-kDa protein (507 amino acid residues) with 12 transmembrane regions. BetL exhibits significant sequence homologies to other glycine betaine transporters, including OpuD from Bacillus subtilis (57% identity) and BetP from Corynebacterium glutamicum (41% identity). These high-affinity secondary transporters form a subset of the trimethylammonium transporter family specific for glycine betaine, whose substrates possess a fully methylated quaternary ammonium group. The observed Km value of 7.9 microM for glycine betaine uptake after heterologous expression of betL in E. coli MKH13 is consistent with values obtained for L. monocytogenes in other studies. In addition, a betL knockout mutant which is significantly affected in its ability to accumulate glycine betaine in the presence or absence of NaCl has been constructed in L. monocytogenes. This mutant is also unable to withstand concentrations of salt as high as can the BetL+ parent, signifying the role of the transporter in Listeria osmotolerance.
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Full list of authors on original publication

C Hill, T Abee, C G Gahan, R D Sleator

Experts in our system

Colin Hill
University College Cork
Total Publications: 351
Cormac G M Gahan
University College Cork
Total Publications: 109
Roy D. Sleator
University College Cork
Total Publications: 44