Escherichia coli Mutants Defective in Dipeptidyl Carboxypeptidase

Two independent mutants of Escherichia coli deficient in dipeptidyl carboxypeptidase activity (Dcp-) were isolated after mutagenesis with ethyl methanesulfonate. Mating experiments and introduction of specific episomes indicated that the responsible gene was located at approximately 27-31 min on the...

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Bibliographic Details
Published in:Proceedings of the National Academy of Sciences - PNAS 1978-12, Vol.75 (12), p.5998-6001
Main Authors: Deutch, Charles E., Soffer, Richard L.
Format: Article
Language:English
Subjects:
Angiotensin-Converting Enzyme Inhibitors
Biochemistry
Chemical suspensions
Chromosomes
Endopeptidases - genetics
Endopeptidases - metabolism
Enzyme activity
Enzymes
Escherichia coli
Escherichia coli - enzymology
Escherichia coli - genetics
Genes
Genetic mutation
Mutation
Nitrogen
Periplasm
Proline - analogs & derivatives
Proline - pharmacology
Protease Inhibitors - pharmacology
Substrate Specificity
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Summary:Two independent mutants of Escherichia coli deficient in dipeptidyl carboxypeptidase activity (Dcp-) were isolated after mutagenesis with ethyl methanesulfonate. Mating experiments and introduction of specific episomes indicated that the responsible gene was located at approximately 27-31 min on the E. coli chromosome. The Dcp- mutants differed from the parental strain in their inability to grow with N-acetylalanylalanylalanine as the sole nitrogen source. Revertants selected for growth on this substrate of the enzyme were found to have reacquired the activity. Enzyme activity was highly sensitive to inhibition by 1-(D-3-mercapto-2-methylpropanoyl)-L-proline (SQ 14225), a potent inhibitor of mammalian dipeptidyl carboxypeptidase (angiotensin-converting enzyme, peptidyl dipeptidase, EC 3.4.15.1). This compound also reduced the rate of growth of the wild type with N-acetylalanylalanylalanine but not with ammonium sulfate. A fraction of the enzyme was released into the medium by osmotic shock, indicating that its presence in the periplasmic space may account for growth with N-acetylated peptides that cannot be taken up by E. coli. In addition to providing information about the specific role of this exopeptidase in E. coli, the Dcp- mutants may prove useful for delineating the regulation and cellular function of dipeptidyl carboxypeptidases in higher organisms.
ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.75.12.5998