A lowered concentration of cAMP receptor protein caused by glucose is an important determinant for catabolite repression in <i>Escherichia coli</i>

Ishizuka, Hitoshi; Hanamura, Akemi; Kunimura, Tadashi; Aiba, Hirofumi

doi:10.1111/j.1365-2958.1993.tb01960.x

Cited by 90 publications

(124 citation statements)

References 31 publications

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“…This indicates that during diauxic growth the variation of cAMP concentration is much more important than the variation of CRP concentrations, which have almost no effect. This is in accordance with results from Ishizuka et al (19) who reported that variation of cAMP concentration is responsible for transient repression, whereas the lowering of the CRP concentration becomes important for permanent repression. This indicates that the regulation by variation of cAMP concentrations is important for fast, dynamic processes, e.g.…”

Section: Regulation Of Pts Operon and Ptsg Expression By Camp⅐crp Andsupporting

confidence: 82%

A Quantitative Approach to Catabolite Repression in Escherichia coli

Bettenbrock

Fischer

Kremling

et al. 2006

Journal of Biological Chemistry

133

156

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A dynamic mathematical model was developed to describe the uptake of various carbohydrates (glucose, lactose, glycerol, sucrose, and galactose) in Escherichia coli. For validation a number of isogenic strains with defined mutations were used. By considering metabolic reactions as well as signal transduction processes influencing the relevant pathways, we were able to describe quantitatively the phenomenon of catabolite repression in E. coli. We verified model predictions by measuring time courses of several extraand intracellular components such as glycolytic intermediates, EII-A Crr phosphorylation level, both LacZ and PtsG concentrations, and total cAMP concentrations under various growth conditions. The entire data base consists of 18 experiments performed with nine different strains. The model describes the expression of 17 key enzymes, 38 enzymatic reactions, and the dynamic behavior of more than 50 metabolites. The different phenomena affecting the phosphorylation level of EIIA Crr , the key regulation molecule for inducer exclusion and catabolite repression in enteric bacteria, can now be explained quantitatively.Catabolite repression in Escherichia coli designates the observation that if different carbohydrates are present in a medium under unlimited conditions, one of them is usually taken up preferentially. Although the fundamental biochemical principles of the regulatory network have been revealed, a quantitative description of this growth behavior is still missing. The center of the regulatory network is formed by the phosphoenolpyruvate (PEP) 4 :carbohydrate phosphotransferase systems (PTS). These systems are involved in both transport and phosphorylation of a large number of carbohydrates, in movement toward these carbon sources (chemotaxis), and in regulation of a number of metabolic pathways (1-3). The PTS in E. coli consist of two common cytoplasmatic proteins, EI (enzyme I) and HPr (histidine-containing protein), as well as an array of carbohydrate-specific EII (enzyme II) complexes. Because all components of the PTS, depending on their phosphorylation status, can interact with various key regulator proteins, the output of the PTS is represented by the degree of phosphorylation of the proteins involved in phosphoryl group transfer, e.g. unphosphorylated EIIA Crr inhibits the uptake of other non-PTS carbohydrates by a process called inducer exclusion. Phosphorylated EIIA Crr activates the adenylate cyclase (CyaA) and leads to an increase in the intracellular cAMP level.Understanding the regulation of carbohydrate uptake requires a quantitative description of the PTS. In this context it is important that the degree of phosphorylation of EIIA Crr is proportional to the PEP/ pyruvate ratio, when no carbohydrates are transported (4) and the respective equilibrium constant is an upper boundary when the PTS is active (5). The PTS should therefore not be regarded as a measure for the transport of PTS substrates but more as a general measure for carbohydrate availability. One feature of our contribution...

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Section: Regulation Of Pts Operon and Ptsg Expression By Camp⅐crp Andsupporting

confidence: 82%

A Quantitative Approach to Catabolite Repression in Escherichia coli

Bettenbrock

Fischer

Kremling

et al. 2006

Journal of Biological Chemistry

133

156

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“…2). The probable reason for the reduction of the activity of the P0 promoter when the mlc-negative strain grows in the presence of glucose is that the concentration of an activator of the P0 promoter, CRP⅐cAMP, was lowered in that condition (1,6). These results also indicated that the action of Mlc in the regulation of the pts operon is dominant over that of CRP⅐cAMP as proposed for the regulation of ptsG expression by Mlc recently (9).…”

Section: Discussionsupporting

confidence: 63%

“…Transcription of the pts promoters increases in the presence of CRP⅐cAMP as well as glucose in vivo (3,4). The glucose-and cAMP-mediated activations occur independently of each other (2,4,5), even though glucose lowers the level of CRP and cAMP in the cell (6). It has been known that the target promoter that is activated when cells are grown in the presence of glucose is the P0 promoter, but the mechanism by which glucose activates the P0 transcription is not known.…”

mentioning

confidence: 99%

Purification of Mlc and Analysis of Its Effects on the pts Expression in Escherichia coli

Kim¹,

Nam²,

Shin³

et al. 1999

Journal of Biological Chemistry

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Products of the pts operon of Escherichia coli have multiple physiological roles such as sugar transport, and the operon is controlled by two promoters, P0 and P1. Expression of the pts P0 promoter that is increased during growth in the presence of glucose is also activated by cAMP receptor protein⅐cAMP. Based on the existence of a sequence that has a high similarity with the known Mlc binding site in the promoter, the effects of the Mlc protein on the pts P0 promoter expression were studied. In vivo transcription assays using wild type and mlc-negative E. coli strains grown in the presence and absence of glucose indicate that Mlc negatively regulates expression of the P0 promoter, and Mlc-dependent repression is relieved by glucose in the growth medium. In vitro transcription assay using purified recombinant Mlc showed that Mlc repressed transcription from the P0 but did not affect the activity of the P1. DNase I footprinting experiments revealed that a Mlc binding site was located around ؉1 to ؉25 of the promoter and that Mlc inhibited the binding of RNA polymerase to the P0 promoter. Cells overexpressing Mlc showed a very slow fermentation rate compared with the wild type when grown in the presence of various phosphoenolpyruvate-carbohydrate phosphotransferase system sugars but few differences in the presence of non-phosphoenolpyruvate-carbohydrate phosphotransferase system sugars except maltose. These results suggest that the pts operon is one of major targets for the negative regulation by Mlc, and thus Mlc regulates the utilization of various sugars as well as glucose in E. coli. The possibility that the inducer of Mlc may not be sugar or its derivative but an unknown factor is proposed to explain the Mlc induction mechanism by various sugars.

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“…To solubilize cells, the cell suspensions were mixed with 500 L of 2 2 loading buffer (4% SDS, 10% 2-mercaptoethanol, 125 mM Tris-HCl, pH 8.0, 20% glycerol, 0.2% bromophenol blue) and heated for 10 min at 100 8 C. Total proteins of the indicated amount were loaded onto 0.1% SDS-13% polyacrylamide gels and electrophoresed. After electrophoresis, Western blotting was performed as described previously (Ishizuka et al 1993), using a polyclonal anti-CRP antibody and a horseradish peroxidaseconjugated secondary antibody.…”

Section: Immunoblot Analysis Of Crpmentioning

confidence: 99%

Mechanism responsible for glucose–lactose diauxie in Escherichia coli: challenge to the cAMP model

1996

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Background : The inhibition of¯-galactosidase expression in glucose-lactose diauxie is a typical example of the glucose effect in Escherichia coli. It is generally believed that glucose exerts its effect at least partly by reducing the intracellular cAMP level. However, there is no direct evidence that the inhibitory effect of glucose on the expression of the lac operon is mediated by a reduction of the cAMP level in the glucose-lactose system.

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A lowered concentration of cAMP receptor protein caused by glucose is an important determinant for catabolite repression in Escherichia coli

Cited by 90 publications

References 31 publications

A Quantitative Approach to Catabolite Repression in Escherichia coli

A Quantitative Approach to Catabolite Repression in Escherichia coli

Purification of Mlc and Analysis of Its Effects on the pts Expression in Escherichia coli

Mechanism responsible for glucose–lactose diauxie in Escherichia coli: challenge to the cAMP model

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