Bacterial Amino Acid Transport Systems

Landick, Robert; Oxender, Dale L.; Ames, Giovanna Ferro‐Luzzi

doi:10.1007/978-1-4684-4601-2_17

Cited by 13 publications

(18 citation statements)

References 218 publications

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“…Also, an extensive comparison of the amino acid sequences of the MalF protein, a membrane component of the maltose transport system, with the membrane components of the histidine transport system (HisP, HisQ, and HisM) of S. typhimurium, as well as to other inner membrane nontransport proteins, showed, again, no significant homology (10). It has been hypothesized that all periplasmic transport systems may have originated from a common ancestor system (18). If this hypothesis is correct, it appears that the transmembrane transport proteins of the various systems have retained their hydrophobic natures rather than specific amino acid sequences.…”

Section: Resultsmentioning

confidence: 99%

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Cloning and characterization of livH, the structural gene encoding a component of the leucine transport system in Escherichia coli

Nazos¹,

Antonucci²,

Landick³

et al. 1986

J Bacteriol

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The physical location of the genetically defined livH gene was mapped in the 17-kilobase plasmid pOX1 by using transposon Tn5 inactivation mapping and further confirmed by subcloning and complementation analysis. These results indicated that the livH gene maps 3' to livK, the gene encoding the leucine-specific binding protein. Moreover, the nucleotide sequence of the livH gene and its flanking regions was determined. The livH gene is encoded starting 47 base pairs downstream from the livK gene, and it is transcribed in the same direction as the livK gene. The livK-livH intergenic region lacks promoter sequences and contains a GC-rich sequence that could lead to the formation of a stable stem loop structure. The coding sequence of the livH gene, which is 924 base pairs, specifies a very hydrophobic protein of 308 amino acid residues. Expression of livH-containing plasmids in minicells suggested that a poorly expressed protein with an Mr of 30,000 could be the livH gene product.

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Section: Resultsmentioning

confidence: 99%

“…Although several binding protein-dependent transport systems have been studied in bacteria, the molecular basis of the transport process is not yet well understood (1,3,18,19). It is known, however, that these systems utilize both periplasmic binding proteins and membrane-associated components.…”

mentioning

confidence: 99%

Cloning and characterization of livH, the structural gene encoding a component of the leucine transport system in Escherichia coli

Nazos¹,

Antonucci²,

Landick³

et al. 1986

J Bacteriol

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“…acids, in general, have lower binding affinities for transport in bacteria (17)(18)(19). Even for GABA, a much lower affinity (Km = 12,000 nM) has been described in an Escherichia coli mutant (21) than the one reported here for a strain of P. fluorescens (Km = 65 nM).…”

Section: Resultsmentioning

confidence: 63%

“…To determine if GABA was interacting with a nonspecific rather than a specific GABA site, amino acids that have a structural resemblance to GABA and have well-defined bacterial transport systems (17)(18)(19) were tested as competitors. Except for a minimal amount of competition by glutamic acid, none of the others (glycine, aspartic acid, asparagine, glutamine, or proline) demonstrated activity.…”

Section: Resultsmentioning

confidence: 99%

gamma-Aminobutyric acid uptake by a bacterial system with neurotransmitter binding characteristics.

Guthrie

Nicholson-Guthrie

1989

Proc. Natl. Acad. Sci. U.S.A.

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ABSTRACTy-Aminobutyric acid (GABA), an amino acid, has been found in every class of living organisms. In higher organisms, GABA is a neurotransmitter and binds with high affinity and specificity to GABA receptors on neurons in a sodium-independent reaction that is saturable. The role of GABA in organisms lacking nervous tissue is not known. This report describes, in a strain of Pseudomonas fluorescens, a GABA uptake system with binding characteristics like those of the GABA (type A) brain receptor. The binding was saturable and specific for GABA, was sodium-independent, was of high affinity (Km = 65 nM), and was inhibited competitively by muscimol, a potent GABA analogue. The bacterial GABA system included a homogeneous binding site, and no cooperative interaction was found between sites. To our knowledge, such a system for GABA, or other neurotransmitters, in a bacterium has not been reported.

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“…The LIV-I permease system mediates the high-affinity transport of leucine across the inner membrane of Escherichia coli by interactions of periplasmic binding proteins with a set of membrane-associated proteins (19). Genes for the periplasmic and membrane proteins lie in a cluster at 76 min on the E. coli chromosome map (2).…”

mentioning

confidence: 99%

Premature termination of in vivo transcription of a gene encoding a branched-chain amino acid transport protein in Escherichia coli

Williamson

Oxender

1992

J Bacteriol

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Previous studies have suggested that control of expression of genes of the LIV-I permease system for the high-affinity transport of branched-chain amino acids in Escherichia coli involves modulation in the frequency of mRNA elongation. Mutation of the Rho transcription termination factor and shortages of charged leucyl-tRNA have been shown to alter LIV-I transport activity. Rho-dependent transcription termination regulated by shortages of charged leucyl-tRNA at sites preceding structural genes has been proposed to account for their role in regulation of LIV-I transport. Transcription of the livJ-binding protein gene, encoding one of the periplasmic components of the LIV-I system, was analyzed in vivo with strains which lack repression of the LIV-I genes and harbor a temperature-sensitive allele for either leucyl-tRNA synthetase or Rho factor. Analysis of mRNA synthesis by DNA-RNA hybridization in the various mutant strains indicated that both shortages of leucyl-tRNA caused by inactivation of the temperature-sensitive leucyl-tRNA synthetase and inactivation of the Rho factor were associated with increased synthesis of livJ mRNA. Nuclease protection and gel electrophoresis studies detected prematurely terminated transcripts corresponding in size to the leader region of livJ mRNA. Accumulations of these short transcripts were suppressed in strains harboring temperature-sensitive alleles for either leucyl-tRNA synthetase or Rho factor. These results provide support for the hypothesis that expression of livJ involves Rho-dependent transcription termination in which antitermination is associated with the intracellular availability of aminoacyl leucyl-tRNA.

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Bacterial Amino Acid Transport Systems

Cited by 13 publications

References 218 publications

Cloning and characterization of livH, the structural gene encoding a component of the leucine transport system in Escherichia coli

Cloning and characterization of livH, the structural gene encoding a component of the leucine transport system in Escherichia coli

gamma-Aminobutyric acid uptake by a bacterial system with neurotransmitter binding characteristics.

Premature termination of in vivo transcription of a gene encoding a branched-chain amino acid transport protein in Escherichia coli

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