Abstract
A series of mutations has been isolated that confer upon amino-acid auxotrophs of Escherichia coli K-12 the ability to grow when fed various D-amino acids. Several distinct systems, mediating cellular use of the D-isomers of leucine, histidine, phenylalanine, tyrosine, tryptophan, isoleucine, and valine, can be mutationally activated. Mutations leading to D-tryptophan use (dadR) all map near purB. They result in high activities of an enzyme that deaminates D-amino acids. Neither the enzymes of the tryptophan biosynthetic pathway nor tryptophanase (EC 4.2.1.e) are involved in D-tryptophan utilization.
MeSH terms
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Amino Acids / metabolism*
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Arginine / metabolism
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Chromosome Mapping
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Coliphages
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D-Amino-Acid Oxidase / analysis
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Escherichia coli / enzymology
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Escherichia coli / metabolism*
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Genetic Linkage
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Genotype
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Histidine / metabolism
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Isoleucine / metabolism
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Isomerism
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Leucine / metabolism
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Lysine / metabolism
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Mutation*
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Phenylalanine / metabolism
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Proline / metabolism
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Serine / metabolism
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Threonine / metabolism
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Transduction, Genetic
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Tryptophan / metabolism
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Tyrosine / metabolism
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Valine / metabolism
Substances
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Amino Acids
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Isoleucine
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Threonine
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Tyrosine
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Serine
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Phenylalanine
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Histidine
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Tryptophan
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Arginine
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Proline
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D-Amino-Acid Oxidase
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Leucine
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Valine
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Lysine