Expression of the Escherichia coli dam gene


  • Anders Løbner-Olesen,

    Corresponding author
    1. Department of Microbiology, The Technical University of Denmark, DK-2800 Lyngby, Copenhagen, Denmark.
    • *Present address (for correspondence); Department of Molecular, Cellular and Developmental Biology, Porter Biosciences Building, University of Colorado at Boulder, Campus Box 347, Boulder, Colorado 80309-0347. USA. Tel. (303) 492 7953; Fax (303) 492 7744.

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  • Erik Boye,

    1. Department of Biophysics, Institute for Cancer Research, Montebello. 0310 Oslo, Norway.
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  • M. G. Marinus

    1. Department of Pharmacology, University of Massachusetts Medical School, 55 Lake Avenue, Worcester, Massachusetts 01655, USA.
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The Escherichia coli dam gene and upstream sequences were cloned from the Kohara phage 4D4. Five promoters were found to contribute to dam gene transcription. PI and P2 (the major promoter) were situated approximately 3.5 kb upstream of the structural gene, P3 was within the aroB gene, P4 was within the urf74.3 gene, and P5 was in the urf74.3-dam intergenic region. The nucleotide sequence of 2280 bp of DNA containing P1 and P2, was determined and shown to have the potential to encode a protein of approximately 16 kDa between P1, P2, and the aroB gene. This 16 kDa open reading frame has been Identified as aroK, the gene for shikimic acid kinase I. Thus the dam gene is part of an operon containing aroK, aroB, urf74.3, and dam. The transcriptional start points of the promoters were determined. A comparison of their nucleotide sequences suggested that P1-P4 were all recognized by the σ70 subunit of the RNA polymerase.