Genetic and biochemical analysis of peptide transport in Escherichia coli
E. coli peptide transport mutants have been isolated based on their resistance to toxic tripeptides. These genetic defects were found to map in two distinct chromosomal locations. The transport systems which require expression of the trp-linked opp genes and the oppE gene(s) for activity were shown to have different substrate preferences. Growth of E. coli in medium containing leucine results in increased entry of exogenously supplied tripeptides into the bacterial cell. This leucine-mediated elevation of peptide transport required expression of the trp-linked opp operon and was accompanied by increased sensitivity to toxic tripeptides, by an enhanced capacity to utilize nutritional peptides, and by an increase in both the velocity and apparent steady-state level of L-(U-/sup 14/C)alanyl-L-alanyl-L-alanine accumulation for E. coli grown in leucine-containing medium relative to these parameters of peptide transport measured with bacteria grown in media lacking leucine. Direct measurement of opp operon expression by pulse-labeling experiments demonstrated that growth of E. coli in the presence of leucine resulted in increased synthesis of the oppA-encoded periplasmic binding protein. The transcriptional regulation of the trp-linked opp operon of E. coli was investigated using lambda placMu51-generated lac operon fusions. Synthesis of ..beta..-galactosidase by strains harboring oppA-lac, oppB-lac, and oppD-lac fusions occurred at a basal level when the fusion-containing strains were grown in minimal medium.
- Research Organization:
- North Carolina Univ., Chapel Hill (USA)
- OSTI ID:
- 6788538
- Resource Relation:
- Other Information: Thesis (Ph. D.)
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ESCHERICHIA COLI
BIOCHEMISTRY
GENETIC MAPPING
CARBON 14 COMPOUNDS
LEUCINE
MEMBRANE TRANSPORT
MUTANTS
PEPTIDES
TRANSCRIPTION
AMINO ACIDS
BACTERIA
CARBOXYLIC ACIDS
CHEMISTRY
LABELLED COMPOUNDS
MAPPING
MICROORGANISMS
ORGANIC ACIDS
ORGANIC COMPOUNDS
PROTEINS
550701* - Microbiology- Tracer Techniques