f Regulation of Escherichia Coli Adenylate Cyclase Activity during Hexose Phosphate Transport
- Authors: Valérie Dumay†, Antoine Danchin, Martine Crasnier‡,* *
- *Author for correspondence: Martine Crasnier. Tel: +1 619 534 2608. Fax: +1 619 534 7108. e-mail: firstname.lastname@example.org
- First Published Online: 01 March 1996, Microbiology 142: 575-583, doi: 10.1099/13500872-142-3-575
- Subject: Physiology And Growth
- Issue Published:
In Escherichia coli cAMP levels vary with the carbon source used in the culture medium. These levels are dependent on the cellular concentration of phosphorylated EnzymeIIAglc, a component of the glucose-phosphotransferase system, which activates adenylate cyclase (AC). When cells are grown on glucose 6-phosphate (Glc6P), the cAMP level is particularly low. In this study, we investigated the mechanism leading to the low cAMP level when Glc6P is used as the carbon source, i.e. the mechanism preventing the activation of AC by phosphorylated EnzymellAglc. Glc6P is transported via the Uhp system which is inducible by extracellular Glc6P. The Uhp system comprises a permease UhpT and three proteins UhpA, UhpB and UhpC which are necessary for uhpT gene transcription. Controlled expression of UhpT in the absence of the regulatory proteins (UhpA, UhpB and UhpC) allowed us to demonstrate that (i) the Uhp regulatory proteins do not prevent the activation of AC by direct interaction with EnzymellAglc and (ii) an increase in the amount of UhpT synthesized (corresponding to an increase in the amount of Glc6P transported) correlates with a decrease in the cAMP level. We present data indicating that Glc6P per se or its degradation is unlikely to be responsible for the low cAMP level. It is concluded that the level of cAMP in the cell is determined by the flux of Glc6P through UhpT.
Present address: University of California San Diego, Department of Biology, La Jolla, CA 92093-0116, USA.
Present address: RITE, 9-2 Kizugawadai, Kizu-cho, Soraku-gun, Kyoto 619-02, Japan.
- Keyword(s): glucose 6-phosphate transport, Escherichia coli, phosphotransferase system, adenylate cyclase, cyclic AMP
© Society for General Microbiology 1996 | Published by the Microbiology Society
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