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Escherichia coli dihydroxyacetone kinase controls gene expression by binding to transcription factor DhaR.

ABSTRACT: Dihydroxyacetone (Dha) kinases are a sequence-conserved family of enzymes, which utilize either ATP (in animals, plants, bacteria) or the bacterial phosphoenolpyruvate carbohydrate phosphotransferase system (PTS) as a source of high-energy phosphate. The PTS-dependent kinase of Escherichia coli consists of three subunits: DhaK contains the Dha binding site, DhaL contains ADP as cofactor for the double displacement of phosphate from DhaM to Dha, and DhaM provides a phospho-histidine relay between the PTS and DhaL::ADP. DhaR is a transcription activator belonging to the AAA+ family of enhancer binding proteins. It stimulates transcription of the dhaKLM operon from a sigma70 promoter and autorepresses dhaR transcription. Genetic and biochemical studies indicate that the enzyme subunits DhaL and DhaK act antagonistically as coactivator and corepressor of the transcription activator by mutually exclusive binding to the sensing domain of DhaR. In the presence of Dha, DhaL is dephosphorylated and DhaL::ADP displaces DhaK and stimulates DhaR activity. In the absence of Dha, DhaL::ADP is converted by the PTS to DhaL::ATP, which does not bind to DhaR.

SUBMITTER: Bachler C

PROVIDER: S-EPMC545809 | biostudies-other | 2005 Jan

REPOSITORIES: biostudies-other

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Escherichia coli dihydroxyacetone kinase controls gene expression by binding to transcription factor DhaR.

Bächler Christoph C Schneider Philipp P Bähler Priska P Lustig Ariel A Erni Bernhard B

The EMBO journal 20041216 2

Dihydroxyacetone (Dha) kinases are a sequence-conserved family of enzymes, which utilize either ATP (in animals, plants, bacteria) or the bacterial phosphoenolpyruvate carbohydrate phosphotransferase system (PTS) as a source of high-energy phosphate. The PTS-dependent kinase of Escherichia coli consists of three subunits: DhaK contains the Dha binding site, DhaL contains ADP as cofactor for the double displacement of phosphate from DhaM to Dha, and DhaM provides a phospho-histidine relay between ...[more]

PMID: 15616579

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Project description:In this work, we shed light on the metabolism of dihydroxyacetone (DHA), a versatile, ubiquitous, and important intermediate for various chemicals in industry, by analyzing its metabolism at the system level in Escherichia coli Using constraint-based modeling, we show that the growth of E. coli on DHA is suboptimal and identify the potential causes. Nuclear magnetic resonance analysis shows that DHA is degraded nonenzymatically into substrates known to be unfavorable to high growth rates. Transcriptomic analysis reveals that DHA promotes genes involved in biofilm formation, which may reduce the bacterial growth rate. Functional analysis of the genes involved in DHA metabolism proves that under the aerobic conditions used in this study, DHA is mainly assimilated via the dihydroxyacetone kinase pathway. In addition, these results show that the alternative routes of DHA assimilation (i.e., the glycerol and fructose-6-phosphate aldolase pathways) are not fully activated under our conditions because of anaerobically mediated hierarchical control. These pathways are therefore certainly unable to sustain fluxes as high as the ones predicted in silico for optimal aerobic growth on DHA. Overexpressing some of the genes in these pathways releases these constraints and restores the predicted optimal growth on DHA.IMPORTANCE DHA is an attractive triose molecule with a wide range of applications, notably in cosmetics and the food and pharmaceutical industries. DHA is found in many species, from microorganisms to humans, and can be used by Escherichia coli as a growth substrate. However, knowledge about the mechanisms and regulation of this process is currently lacking, motivating our investigation of DHA metabolism in E. coli We show that under aerobic conditions, E. coli growth on DHA is far from optimal and is hindered by chemical, hierarchical, and possibly allosteric constraints. We show that optimal growth on DHA can be restored by releasing the hierarchical constraint. These results improve our understanding of DHA metabolism and are likely to help unlock biotechnological applications involving DHA as an intermediate, such as the bioconversion of glycerol or C1 substrates into value-added chemicals.

Dataset Information

Escherichia coli dihydroxyacetone kinase controls gene expression by binding to transcription factor DhaR.

Publications

Escherichia coli dihydroxyacetone kinase controls gene expression by binding to transcription factor DhaR.

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