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The Trehalose Phosphotransferase System (PTS) in E. coli W Can Transport Low Levels of Sucrose that Are Sufficient to Facilitate Induction of the csc Sucrose Catabolism Operon

Plasticity in substrate acceptance is a well-characterised phenomenon for disaccharide transporters. Sucrose, a non-reducing disaccharide, is usually metabolised via either the permease-mediated chromosomally-encoded sucrose catabolism (csc) regulon or the sucrose phosphotransferase system (PTS). E....

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Detalles Bibliográficos
Autores principales: Steen, Jennifer A., Bohlke, Nina, Vickers, Claudia E., Nielsen, Lars K.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Public Library of Science 2014
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3938415/
https://www.ncbi.nlm.nih.gov/pubmed/24586369
http://dx.doi.org/10.1371/journal.pone.0088688
Descripción
Sumario:Plasticity in substrate acceptance is a well-characterised phenomenon for disaccharide transporters. Sucrose, a non-reducing disaccharide, is usually metabolised via either the permease-mediated chromosomally-encoded sucrose catabolism (csc) regulon or the sucrose phosphotransferase system (PTS). E. coli W is a fast-growing strain which efficiently utilises sucrose at concentrations above 1% via the csc regulon. To examine if sucrose could be metabolised via other routes, a library of transposon mutants was generated and screened on 0.2% sucrose. One mutant identified from this library had an insertion in the repressor for the regulon controlling catabolism of the disaccharide trehalose (treR). A series of mutants was constructed to elucidate the mechanism of sucrose utilization in the treR insertion strain. Analysis of these mutants provided evidence that deletion of TreR enables uptake of sucrose via TreB, an enzyme II protein required for PTS-mediated uptake of trehalose. Once inside the cell, this sucrose is not processed by the TreC hydrolase, nor is it sufficient for growth of the strain. QRT-PCR analysis showed that levels of cscA (invertase) transcript increased in the WΔtreR mutant relative to the wild-type strain when grown under low sucrose conditions. This result suggests that the intracellular sucrose provided by TreB can facilitate de-repression of the csc regulon, leading to increased gene expression, sucrose uptake and sucrose utilization in the treR mutant.