Archives of Microbiology

, Volume 176, Issue 5, pp 370–376

Expression of the pho regulon interferes with induction of the uhpT gene in Escherichia coli K-12

Authors

  • Sally M. Hoffer
    • Department of Molecular Microbiology, Utrecht University, 3584 CH Utrecht, The Netherlands
  • Nathalie Uden
    • Department of Molecular Microbiology, Utrecht University, 3584 CH Utrecht, The Netherlands
  • Jan Tommassen
    • Department of Molecular Microbiology, Utrecht University, 3584 CH Utrecht, The Netherlands
Original Paper

DOI: 10.1007/s002030100339

Cite this article as:
Hoffer, S.M., Uden, N. & Tommassen, J. Arch Microbiol (2001) 176: 370. doi:10.1007/s002030100339

Abstract.

The uptake of hexose 6-phosphates in Escherichia coli is mediated by the transporter UhpT, the synthesis of which is induced by the presence of glucose 6-phosphate (glucose 6-P) in the medium. Since this protein functions as an anion exchanger, it is generally assumed to be geared for the use of sugar phosphates as a carbon source. However, the question was unresolved whether this transporter can also provide the cells with glucose 6-P as a phosphate source. It is demonstrated in this work that UhpT-mediated glucose 6-P uptake does not allow the cells to grow on glucose 6-P as phosphate source. Hence, the expression of UhpT under phosphate limitation would not be particularly advantageous and some form of interaction between the uhp system and the Pi-limitation-inducible pho regulon, the products of which are involved in phosphate acquisition, may be anticipated. Indeed, the use of an uhpT-lacZ fusion revealed that much higher concentrations of the inducer glucose 6-P were required to elevate uhpT transcription when the pho regulon was expressed. This interference was the result of degradation of glucose 6-P by one of the products of the pho regulon, the periplasmic enzyme alkaline phosphatase. The specific form of interaction between the Pho and Uhp systems is designated inducer degradation.

uhp genes pho regulon Inducer degradation Escherichia coli

Copyright information

© Springer-Verlag 2001