An insight into the role of phosphotransacetylase (pta) and the acetate/acetyl-CoA node in Escherichia coli

Castaño-Cerezo, Sara; Pastor, José M.; Renilla, Sergio; Bernal, Vicente; Iborra, José L.; Cánovas, Manuel

doi:10.1186/1475-2859-8-54

Cited by 118 publications

(87 citation statements)

References 61 publications

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“…Improving the cell density of bovine E. coli would enhance the applicability of the vaccine to the cattle industry. The cell density is limited by acetate, a primary inhibitory metabolite that accumulates in E. coli cultures, which was caused of acetate inhibition for DNA transcription, RNA translation, protein stability and compound synthesis [3] . The acetate accumulation can be reduced by optimizing the culture conditions and genetically modifying the cells [4][5][6] .…”

Section: Introductionmentioning

confidence: 99%

“…In E. coli, acetate is formed via two pathways: the phosphotransacetylaseacetate kinase (Pta-AckA) pathway and the pyruvate oxidase B (PoxB) pathway, which use acetyl-CoA and pyruvate as substrate, respectively [7,8] . Conversely, reducing the carbon flux in the Embden-Meyerhof pathway (EMP) reducing of the acetate excretion by lowering the pyruvate production [3,9] . Acetate synthesis and its metabolic flux distribution are affected from the values of the culture parameters [8,10] .…”

Section: Introductionmentioning

confidence: 99%

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Sığırlarda Escherchia coli’nin Yüksek Hücre Yoğunluğunda Fermentasyonu İçin En Uygun Kültür Koşullarının Sağlanması

Liu¹,

Li²,

Xia³

et al. 2018

Kafkas Univ Vet Fak Derg

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Bovine Escherichia coli infection, which causes major economic losses to the cattle industry each year, can be prevented by administering formalin-inactivated vaccine. However, to enhance the application of this vaccine, the cell density of the formalin-inactivated E. coli should be boosted. This can be achieved by reducing the accumulation of acetate, a primary inhibitory metabolite in E. coli fermentation. To this end, the present study investigated the effect of pH, dissolved oxygen (DO) levels, and feeding methods on bovine E. coli fermentation, and developed two-stage pH and DO control strategies and a combined pH-and DO-mediated feeding strategy for the fermentation. The optimized conditions for Bovine E. coli were pH 7.0 at 0-10 h, 6.5 at 10-24 h; DO 50% at 0-10 h, 30% at 10-24 h; pH and DO feedback feeding at 0-10 h and 10-24 h, respectively. With Bovine E. coli fermentation under the optimized conditions, the acetate accumulation was 1.12 g/L and the cell density was 36.47 (OD600), which were 59.12% lower and 77.29% higher than these with the original conditions (pH 7.0; DO 20%; residual glucose concentration maintained at 2.0 g/L). After analyzing the main nodes of acetate synthesis, it was found that the lower carbon flux enters the Embden-Meyerhof pathway. Under the optimized conditions, the pyruvate flux and acetyl-CoA synthesis were low, and much of the acetyl-CoA participated in the tricarboxylic acid cycle. The extracellular acetate flux was 8.3%, which was 65.13% lower than in the original conditions. Keywords: Escherichia coli, Acetate, Dissolved oxygen, Feeding strategy, Metabolic flux distribution Sığırlarda Escherchia coli'nin Yüksek Hücre Yoğunluğunda Fermentasyonu İçin En Uygun Kültür Koşullarının Sağlanması ÖzSığırlardaki Escherchia coli enfeksiyonları her yıl sığırcılık sektörünü büyük çaplı maddi zarara uğratmakla birlikte, formalinle etkisizleştirilmiş bakteriden yapılan aşıyla önlenebilmektedir. Ancak, bu aşının etkisini artırmak için formalinde etkisizleştirmiş E. coli hücre yoğunluğunun artırılması gerekmektedir. Bunu elde etmek için E. coli fermentasyonunu baskılayan birincil bir metabolik ürün olan asetatın birikimi azaltılmalıdır. Bu amaçla, mevcut çalışmada pH, çözünmüş oksijen (ÇO) düzeyleri ve beslenme şeklinin sığırlardaki E. coli fermentasyonuna etkileri araştırılmış ve iki aşamalı bir pH ve ÇO kontrolü stratejisi geliştirilerek pH ve ÇO düzeylerini birlikte değerlendiren bir beslenme planı ile fermentasyonun artırılması yoluna gidilmiştir. Sığır E. coli için optimize edimiş koşullar pH için 0-10 saat aralığında 7.0, 10-24 saat aralığında 6.5; ÇO için 0-10 saat aralığında %50, 10-24 saat aralığında %30, pH ve ÇO temelinde besleme için sırasıyla 0-10 saat ve 10-24 saat olarak belirlendi. Optimize koşullar altında sığır E. coli fermentasyonu ile birlikte asetat birikimi 1.12 g/L olup hücre yoğunluğu 36.47 (OD600) olarak tespit edildi. Bu değerler orjinal koşullardan (pH 7.0; ÇO %20; kalıntı glukoz derişimi 2.0 g/L'de tutulmuş) sırasıyla %59.12 daha düşük ve %77.29 daha...

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Sığırlarda Escherchia coli’nin Yüksek Hücre Yoğunluğunda Fermentasyonu İçin En Uygun Kültür Koşullarının Sağlanması

Liu¹,

Li²,

Xia³

et al. 2018

Kafkas Univ Vet Fak Derg

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“…[12] The excretion of acetate results in deficient utilization of carbon sources and inhibition of cellular growth and protein production. [13] Many studies have reported a highyield production of recombinant proteins obtained by reduction of the acetate accumulation.…”

Section: Introductionmentioning

confidence: 99%

“…[13] Many studies have reported a highyield production of recombinant proteins obtained by reduction of the acetate accumulation. [12] The pathways of phosphotransacetylaseÀacetate kinase (PtaÀAckA)…”

Section: Introductionmentioning

confidence: 99%

Optimization of culture conditions to improve the expression level of beta1–epsilon toxin ofClostridium perfringenstype B inEscherichia coli

Chao

Cheng

Wang

et al. 2016

Biotechnology & Biotechnological Equipment

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The detoxified beta1Àepsilon (b1Àe) toxin protein of Clostridium perfringens type B provides protection from C. perfringens types B, C and D infections. Acetate is the primary by-product from the cell growth and expression of b1Àe protein. In the present study, the effects of pH and dissolved oxygen (DO) on the expression of b1-e protein were investigated. Two-stage pH and DO control strategies were developed for the expression of b1Àe protein. The obtained results indicated that higher cell density and concentration of b1-e protein, and lower accumulation of acetate were obtained when pH was maintained at a constant level of 6.5 (0À6 h) and 7.0 (6À16 h), and the DO level was maintained at 60% (0À6 h) and 30% (6À16 h). Furthermore, the impact of intermittent, DO feedback, pH feedback and glucose-stat feeding on the expression of b1Àe protein were studied. By using the DO feedback feeding, combined with the stage control of pH (6.5 for 0À6 h, 7.0 for 6À16 h) and DO (60% for 0À6 h, 30% for 6À16 h), the highest cell density of 2.045 (absorbance at 600 nm) and a b1Àe protein concentration of 63.24 mg/L were obtained, and the accumulation of acetate decreased to 0.872 g/L.

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“…This specific aspect makes it in principle possible to describe strains with different "acetate overflow lines" (e.g. mutants [37,38] or "acetate feeding" strains obtained in evolution experiments [39,40]), which correspond to feasible -albeit suboptimalcellular states that would be harder to describe by the model of [13]. On the other hand, the latter characterizes, in a sense, The respiration phenotype has a large yield (small q) and large specific protein costs, while the fermentation phenotype carries lower yields (higher q) and a smaller cost.…”

mentioning

confidence: 99%

A yield-cost tradeoff governs Escherichia coli's decision between fermentation and respiration in carbon-limited growth

Mori

Marinari

Martino

2017

Preprint

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Many microbial systems are known to actively reshape their proteomes in response to changes in growth conditions induced e.g. by nutritional stress or antibiotics. Part of the re-allocation accounts for the fact that, as the growth rate is limited by targeting specific metabolic activities, cells simply respond by fine-tuning their proteome to invest more resources into the limiting activity (i.e. by synthesizing more proteins devoted to it). However, this is often accompanied by an overall re-organization of metabolism, aimed at improving the growth yield under limitation by re-wiring resource through different pathways. While both effects impact proteome composition, the latter underlies a more complex systemic response to stress. By focusing on E. coli's 'acetate switch', we use mathematical modeling and a re-analysis of empirical data to show that the transition from a predominantly fermentative to a predominantly respirative metabolism in carbon-limited growth results from the trade-off between maximizing the growth yield and minimizing its costs in terms of required the proteome share. In particular, E. coli's metabolic phenotypes appear to be Pareto-optimal for these objective functions over a broad range of dilutions.The physiology of cell growth can nowadays be experimentally probed in exponentially growing bacteria both at bulk (see e.g. the bacterial growth laws detailed in [1][2][3]) and at single cell resolution [4][5][6][7]. Refining the picture developed since the 1950s [8,9], recent studies have shown that changes in growth conditions are accompanied by a massive re-organization of the cellular proteome, whereby resources are re-distributed among protein classes (e.g. transporters, metabolic enzymes, ribosome-affiliated proteins, etc.) so as to achieve optimal growth performance [10]. This in turn underlies significant modifications in cellular energetics to cope with the increasing metabolic burden of fast growth [11][12][13].E. coli's 'acetate switch' is a major manifestation of the existence of a complex interplay between metabolism and gene expression. Slowly growing E. coli cells tend to operate close to the theoretical limit of maximum biomass yield [14,15]. Fast-growing cells, instead, typically show lower yields, together with the excretion of carbon equivalents such as acetate [13]. One can argue that, in the latter regime, cells optimize enzyme usage, i.e. they minimize the protein costs associated to growth, while at slow growth they try to use nutrients as efficiently as possible [13]. As one crosses over from one regime to the other, E. coli's growth physiology appears to be determined to a significant extent by the trade-off between growth and its biosynthetic costs. Interestingly, a similar overflow scenario appears in other cell types in proliferating regimes (see e.g. the Crabtree effect in yeast [16,17] or the Warburg effect in cancer cells [18][19][20]).Several phenomenological models have tackled the issue of how metabolism and gene expression coordinate to optimize growth in ...

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An insight into the role of phosphotransacetylase (pta) and the acetate/acetyl-CoA node in Escherichia coli

Cited by 118 publications

References 61 publications

Sığırlarda Escherchia coli’nin Yüksek Hücre Yoğunluğunda Fermentasyonu İçin En Uygun Kültür Koşullarının Sağlanması

Sığırlarda Escherchia coli’nin Yüksek Hücre Yoğunluğunda Fermentasyonu İçin En Uygun Kültür Koşullarının Sağlanması

Optimization of culture conditions to improve the expression level of beta1–epsilon toxin ofClostridium perfringenstype B inEscherichia coli

A yield-cost tradeoff governs Escherichia coli's decision between fermentation and respiration in carbon-limited growth

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