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Journal of Bacteriology, April 2005, p. 2377-2385, Vol. 187, No. 7
0021-9193/05/$08.00+0     doi:10.1128/JB.187.7.2377-2385.2005
Copyright © 2005, American Society for Microbiology. All Rights Reserved.

The gusBC Genes of Escherichia coli Encode a Glucuronide Transport System

Wei-Jun Liang,1,2 Kate J. Wilson,3 Hao Xie,1 Jan Knol,4 Shun'ichi Suzuki,1 Nicholas G. Rutherford,1 Peter J. F. Henderson,1* and Richard A. Jefferson5

Astbury Centre for Structural Molecular Biology, School of Biochemistry and Molecular Biology, University of Leeds, Leeds,1 Department of Biosciences, University of Kent, Canterbury, Kent, United Kingdom,2 Australian Institute of Marine Science, Queensland,3 CAMBIA (An Affiliated Research Centre of Charles Sturt University), Canberra, Australia,5 Department of Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute, Haren, The Netherlands4

Received 21 April 2004/ Accepted 26 October 2004

Two genes, gusB and gusC, from a natural fecal isolate of Escherichia coli are shown to encode proteins responsible for transport of ß-glucuronides with synthetic [14C]phenyl-1-thio-ß-D-glucuronide as the substrate. These genes are located in the gus operon downstream of the gusA gene on the E. coli genome, and their expression is induced by a variety of ß-D-glucuronides. Measurements of transport in right-side-out subcellular vesicles show the system has the characteristics of secondary active transport energized by the respiration-generated proton motive force. When the genes were cloned together downstream of the tac operator-promoter in the plasmid pTTQ18 expression vector, transport activity was increased considerably with isopropylthiogalactopyranoside as the inducer. Amplified expression of the GusB and GusC proteins enabled visualization and identification by N-terminal sequencing of both proteins, which migrated at ca. 32 kDa and 44 kDa, respectively. Separate expression of the GusB protein showed that it is essential for glucuronide transport and is located in the inner membrane, while the GusC protein does not catalyze transport but assists in an as yet unknown manner and is located in the outer membrane. The output of glucuronides as waste by mammals and uptake for nutrition by gut bacteria or reabsorption by the mammalian host is discussed.

* Corresponding author. Mailing address: Astbury Centre for Structural Molecular Biology, School of Biochemistry and Molecular Biology, University of Leeds, Leeds LS2 9JT, United Kingdom. Phone: 113 343 3175. Fax: 113 343 3175. E-mail: p.j.f.henderson{at}leeds.ac.uk.

Journal of Bacteriology, April 2005, p. 2377-2385, Vol. 187, No. 7
0021-9193/05/$08.00+0     doi:10.1128/JB.187.7.2377-2385.2005
Copyright © 2005, American Society for Microbiology. All Rights Reserved.



This article has been cited by other articles:

  • Beaud, D., Tailliez, P., Anba-Mondoloni, J. (2005). Genetic characterization of the {beta}-glucuronidase enzyme from a human intestinal bacterium, Ruminococcus gnavus. Microbiology 151: 2323-2330 [Abstract] [Full Text]  


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