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Network Biology, 2014, 4(3): 95-108
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Article

Regulatory switches for hierarchical use of carbon sources in E. coli

Ruth S. Perez-Alfaro1, Moises Santillan2, Edgardo Galan-Vasquez1, Agustino Martinez-Antonio1
1Departamento de Ingenieria Genetica, Centro de Investigacion y de Estudios Avanzados del IPN, Unidad Irapuato, Km. 9.6 Libramiento Norte Carr. Irapuato-Leon 36821 Irapuato, Guanajuato, Mexico
2Centro de Investigacion y de Estudios Avanzados del IPN, Unidad Monterrey, Via del Conocimiento 201, 66600 Apodaca NL, Mexico

Received 2 May 2014;Accepted 5 June 2014;Published online 1 September 2014
IAEES

Abstract
In this work we study the preferential use of carbon sources in the bacterium Escherichia coli. To that end we engineered transcriptional fusions of the reporter gene gfpmut2, downstream of transcription-factor promoters, and analyzed their activity under several conditions. The chosen transcription factors are known to regulate catabolic operons associated to the consumption of alternative sugars. The obtained results indicate the following hierarchical order of sugar preference in this bacterium: glucose > arabinose > sorbitol > galactose. Further dynamical results allowed us to conjecture that this hierarchical behavior might be operated by at least the following three regulatory strategies: 1) the coordinated activation of the corresponding operons by the global regulator catabolic repressor protein (CRP), 2) their asymmetrical responses to specific and unspecific sugars and, 3) the architecture of the associated gene regulatory networks.

Keywords Escherichia coli;transcription factors;carbon sources;hierarchical use.


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