Short Communications

Molecular and General Genetics MGG

, Volume 209, Issue 2, pp 403-407

First online:

Nitrogen regulation of transport operons: Analysis of promoters argTr and dhuA

  • Gudrun SchmitzAffiliated withDepartment of Molecular Biology, Boehringer Manheim GmbH, Biochemical Research Center
  • , Peter DürreAffiliated withInstitut für Mikrobiologie, Universität Göttingen
  • , Guy MullenbachAffiliated withChiron Research Laboratories, Chiron Corporation
  • , Giovanna Ferro-Luzzi AmesAffiliated withDepartment of Biochemistry, University of California

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In Salmonella typhimurium the periplasmic permeases for histidine and for lysine-arginine-ornithine are regulated by nitrogen availability. The nature of the dhuA and argTr promoters of the operons coding for these permeases was analyzed by placing the galactokinase gene under their control (in vector pKO-1). argTr was found to respond to nitrogen regulation. We investigated the involvement of a mirror symmetry in argTr in its regulation by nitrogen. It had been postulated previously (Higgins and Ames 1982) that mirror symmetries might act as protein recognition sites important in regulation of gene expression. Here we demonstrate that the mirror symmetry in argTr is not involved in nitrogen control. Contrary to expectation, the galK gene was not regulated by nitrogen when it was placed under dhuA control. Here we propose a possible explanation for this finding.

Key words

Nitrogen regulation Mirror symmetry Periplasmic permease Promoters