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Transcription analysis of central metabolism genes in Escherichia coli. Possible roles of sigma38 in their expression, as a response to carbon limitation.

ABSTRACT: The phosphoenolpyruvate: carbohydrate transferase system (PTS) transports glucose in Escherichia coli. Previous work demonstrated that strains lacking PTS, such as PB11, grow slow on glucose. PB11 has a reduced expression of glycolytic, and upregulates poxB and acs genes as compared to the parental strain JM101, when growing on glucose. The products of the latter genes are involved in the production of AcetylCoA. Inactivation of rpoS that codes for the RNA polymerase sigma(38) subunit, reduces further (50%) growth of PB11, indicating that sigma(38) plays a central role in the expression of central metabolism genes in slowly growing cells. In fact, transcription levels of glycolytic genes is reduced in strain PB11rpoS(-) as compared to PB11. In this report we studied the role of sigma(70) and sigma(38) in the expression of the complete glycolytic pathway and poxB and acs genes in certain PTS(-) strains and their rpoS(-) derivatives. We determined the transcription start sites (TSSs) and the corresponding promoters, in strains JM101, PB11, its derivative PB12 that recovered its growth capacity, and in their rpoS(-) derivatives, by 5'RACE and pyrosequencing. In all these genes the presence of sequences resembling sigma(38) recognition sites allowed the proposition that they could be transcribed by both sigma factors, from overlapping putative promoters that initiate transcription at the same site. Fourteen new TSSs were identified in seventeen genes. Besides, more than 30 putative promoters were proposed and we confirmed ten previously reported. In vitro transcription experiments support the functionality of putative dual promoters. Alternatives that could also explain lower transcription levels of the rpoS(-) derivatives are discussed. We propose that the presence if real, of both sigma(70) and sigma(38) dependent promoters in all glycolytic genes and operons could allow a differential transcription of these central metabolism genes by both sigma subunits as an adaptation response to carbon limitation.

SUBMITTER: Olvera L

PROVIDER: S-EPMC2759082 | biostudies-literature | 2009 Oct

REPOSITORIES: biostudies-literature

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Transcription analysis of central metabolism genes in Escherichia coli. Possible roles of sigma38 in their expression, as a response to carbon limitation.

Olvera Leticia L Mendoza-Vargas Alfredo A Flores Noemí N Olvera Maricela M Sigala Juan Carlos JC Gosset Guillermo G Morett Enrique E Bolívar Francisco F

PloS one 20091019 10

The phosphoenolpyruvate: carbohydrate transferase system (PTS) transports glucose in Escherichia coli. Previous work demonstrated that strains lacking PTS, such as PB11, grow slow on glucose. PB11 has a reduced expression of glycolytic, and upregulates poxB and acs genes as compared to the parental strain JM101, when growing on glucose. The products of the latter genes are involved in the production of AcetylCoA. Inactivation of rpoS that codes for the RNA polymerase sigma(38) subunit, reduces f ...[more]

PMID: 19838295

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Project description:BackgroundThe cellular responses of bacteria to superoxide stress can be used to model adaptation to severe environmental changes. Superoxide stress promotes the excessive production of reactive oxygen species (ROS) that have detrimental effects on cell metabolic and other physiological activities. To antagonize such effects, the cell needs to regulate a range of metabolic reactions in a coordinated way, so that coherent metabolic responses are generated by the cellular metabolic reaction network as a whole. In the present study, we have used a quantitative metabolic flux analysis approach, together with measurement of gene expression and activity of key enzymes, to investigate changes in central carbon metabolism that occur in Escherichia coli in response to paraquat-induced superoxide stress. The cellular regulatory mechanisms involved in the observed global flux changes are discussed.ResultsFlux analysis based on nuclear magnetic resonance (NMR) and mass spectroscopy (MS) measurements and computation provided quantitative results on the metabolic fluxes redistribution of the E. coli central carbon network under paraquat-induced oxidative stress. The metabolic fluxes of the glycolytic pathway were redirected to the pentose phosphate pathway (PP pathway). The production of acetate increased significantly, the fluxes associated with the TCA cycle decreased, and the fluxes in the glyoxylate shunt increased in response to oxidative stress. These global flux changes resulted in an increased ratio of NADPH:NADH and in the accumulation of α-ketoglutarate.ConclusionsMetabolic flux analysis provided a quantitative and global picture of responses of the E. coli central carbon metabolic network to oxidative stress. Systematic adjustments of cellular physiological state clearly occurred in response to changes in metabolic fluxes induced by oxidative stress. Quantitative flux analysis therefore could reveal the physiological state of the cell at the systems level and is a useful complement to molecular systems approaches, such as proteomics and transcription analyses.

Dataset Information

Transcription analysis of central metabolism genes in Escherichia coli. Possible roles of sigma38 in their expression, as a response to carbon limitation.

Publications

Transcription analysis of central metabolism genes in Escherichia coli. Possible roles of sigma38 in their expression, as a response to carbon limitation.

Similar Datasets

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