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.
CITATION STYLE
Hoffer, S. M., Uden, N., & Tommassen, J. (2001). Expression of the pho regulon interferes with induction of the uhpT gene in Escherichia coli K-12. Archives of Microbiology, 176(5), 370–376. https://doi.org/10.1007/s002030100339
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