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International Journal of Microbiology
Volume 2011, Article ID 107023, 9 pages
Research Article

Exposure to Glycolytic Carbon Sources Reveals a Novel Layer of Regulation for the MalT Regulon

Department of Microbiology and Immunology, Stritch School of Medicine, Loyola University Chicago, 2160 S. First Avenue, Building 105, Maywood, IL 60153, USA

Received 16 March 2011; Revised 27 April 2011; Accepted 7 May 2011

Academic Editor: Haichun Gao

Copyright © 2011 Sylvia A. Reimann and Alan J. Wolfe. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Bacteria adapt to changing environments by means of tightly coordinated regulatory circuits. The use of synthetic lethality, a genetic phenomenon in which the combination of two nonlethal mutations causes cell death, facilitates identification and study of such circuitry. In this study, we show that the E. coli ompR malTcon double mutant exhibits a synthetic lethal phenotype that is environmentally conditional. MalTcon, the constitutively active form of the maltose system regulator MalT, causes elevated expression of the outer membrane porin LamB, which leads to death in the absence of the osmoregulator OmpR. However, the presence and metabolism of glycolytic carbon sources, such as sorbitol, promotes viability and unveils a novel layer of regulation within the complex circuitry that controls maltose transport and metabolism.