This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Lloyd, A D Articles by Kadner, R J Search for Related Content PubMed PubMed Citation Articles by Lloyd, A D Articles by Kadner, R J

 Previous Article  |  Next Article 

J Bacteriol. 1990 April; 172(4): 1688-1693

research-article

Topology of the Escherichia coli uhpT sugar-phosphate transporter analyzed by using TnphoA fusions.

Department of Microbiology, School of Medicine, University of Virginia, Charlottesville 22908.

ABSTRACT

The Escherichia coli uhpT protein catalyzes the active transport of sugar-phosphates by an obligatory exchange mechanism. To examine its transmembrane topology, we isolated a collection of uhpT-phoA fusions encoding hybrid proteins of different lengths from the N terminus of UhpT fused to alkaline phosphatase by using transposon TnphoA. These fusions displayed different levels of alkaline phosphatase activity, although comparable levels of full-length UhpT-PhoA proteins were produced in maxicells of both high- and low-activity fusions. The full-length protein species were unstable and were degraded to the size of the alkaline phosphatase moiety in the case of a high-activity fusion or to small fragments in the case of a low-activity fusion. The enzyme activity present in low-activity fusions appeared to result from export of a small proportion of the fusion proteins to the periplasmic space. Although fusions were not obtained in all predicted extramembranous loops, the deduced topology of UhpT was consistent with a model of 12 membrane-spanning regions oriented with the amino and carboxyl termini in the cytoplasm.

This article has been cited by other articles:

• Ouchane, S., Kaplan, S. (1999). Topological Analysis of the Membrane-localized Redox-responsive Sensor Kinase PrrB from Rhodobacter sphaeroides 2.4.1. J. Biol. Chem. 274: 17290-17296 [Abstract] [Full Text]  
• Pan, C.-J., Lin, B., Chou, J. Y. (1999). Transmembrane Topology of Human Glucose 6-Phosphate Transporter. J. Biol. Chem. 274: 13865-13869 [Abstract] [Full Text]  
• Bost, S., Belin, D. (1997). prl Mutations in the Escherichia coli secG Gene. J. Biol. Chem. 272: 4087-4093 [Abstract] [Full Text]  
• van Geest, M., Lolkema, J. S. (1996). Membrane Topology of the Sodium Ion-dependent Citrate Carrier of Klebsiella pneumoniae. EVIDENCE FOR A NEW STRUCTURAL CLASS OF SECONDARY TRANSPORTERS. J. Biol. Chem. 271: 25582-25589 [Abstract] [Full Text]  
• Matos, M., Fann, M.-C., Yan, R.-T., Maloney, P. C. (1996). Enzymatic and Biochemical Probes of Residues External to the Translocation Pathway of UhpT, the Sugar Phosphate Carrier of Escherichia coli. J. Biol. Chem. 271: 18571-18575 [Abstract] [Full Text]  
• Parma, D H, Snyder, M, Sobolevski, S, Nawroz, M, Brody, E, Gold, L (1992). The Rex system of bacteriophage lambda: tolerance and altruistic cell death.. Genes Dev. 6: 497-510 [Abstract]