Metabolic Consequences of Polyphosphate Synthesis and Imminent Phosphate Limitation

Kim, Geun Don; Qiu, Danye; Jessen, Henning J.; Mayer, Andreas

doi:10.1128/mbio.00102-23

Cited by 8 publications

(4 citation statements)

References 118 publications

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“…cerevisiae. Moreover, it can activate the protein kinase A pathway, which regulates cell growth and several associated physiological properties. − In addition, Kim et al reported that phosphate starvation led to reduced accumulation of phosphate-containing nucleotides, nucleoside diphosphates, and nucleoside triphosphates . The results of this study confirm this point.…”

Section: Resultssupporting

confidence: 78%

Promoting Nucleic Acid Synthesis in Saccharomyces cerevisiae through Enhanced Expression of Rrn7p, Rrn11p, IMPDH, and Pho84p

Wang,

Xia,

et al. 2023

J. Agric. Food Chem.

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Saccharomyces cerevisiae has emerged as a preferred source for industrial production of ribonucleic acids (RNAs) and their derivatives, which find wide applications in the food and pharmaceutical sectors. In this study, we employed a modified RNA polymerase I-mediated green fluorescent protein expression system, previously developed by our team, to screen and identify an industrial S. cerevisiae strain with an impressive 18.2% increase in the RNA content. Transcriptome analysis revealed heightened activity of genes and pathways associated with rRNA transcription, purine metabolism, and phosphate transport in the high nucleic acid content mutant strains. Our findings highlighted the crucial role of the transcription factor Sfp1p in enhancing the expression of two key components of the transcription initiation factor complex, Rrn7p and Rrn11p, thereby promoting rRNA synthesis. Moreover, elevated expression of 5′-inosine monophosphate dehydrogenases, regardless of the specific isoform (IMD2, 3, or 4), resulted in increased rRNA synthesis through heightened GTP levels. Additionally, exogenous phosphate application, coupled with overexpression of the phosphate transporter PHO84, led to a 61.4% boost in the RNA yield, reaching 2050.4 mg/L. This comprehensive study provides valuable insights into the mechanism of RNA synthesis and serves as a reference for augmenting RNA production in the food industry.

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Section: Resultssupporting

confidence: 78%

Promoting Nucleic Acid Synthesis in Saccharomyces cerevisiae through Enhanced Expression of Rrn7p, Rrn11p, IMPDH, and Pho84p

Wang,

Xia,

et al. 2023

J. Agric. Food Chem.

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“…By contrast, earlier studies based on unbiased mutagenesis, which subsequently received much less attention, had identified mutations in other regions of PHO81 with significant impact on PHO pathway activation ( Ogawa et al, 1995 ; Spain et al, 1995 ; Toh-E and Oshima, 1974 ; Creasy et al, 1993 ; Creasy et al, 1996 ). The situation is complicated by further studies, which found global IP 7 levels to decrease rather than increase upon P i starvation ( Wild et al, 2016 ; Li et al, 2020 ; Lonetti et al, 2011 ; Kim et al, 2023 ). The analytics used in most studies could not distinguish 1-IP 7 and 5-IP 7 , however, leaving open the possibility that an increase of 1-IP 7 might be masked by a decrease of a much larger pool of 5-IP 7 .…”

Section: Introductionmentioning

confidence: 99%

Inositol pyrophosphate dynamics reveals control of the yeast phosphate starvation program through 1,5-IP8 and the SPX domain of Pho81

Chabert

Kim

Qiu

et al. 2023

eLife

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Eukaryotic cells control cytosolic inorganic phosphate to balance its role as essential macronutrient with its negative bioenergetic impacts. Phosphate homeostasis depends on a conserved signaling pathway including inositol pyrophosphates (PP-IPs) and SPX receptor domains. Since cells synthesize various PP-IPs and SPX domains bind them promiscuously, it is unclear whether a specific PP-IP regulates SPX domains in vivo, or whether multiple PP-IPs act as a pool. In contrast to previous models, which postulated that phosphate starvation is signaled by increased 1-IP7 production, we now show that the levels of all detectable PP-IPs of yeast, 1-IP7, 5-IP7 and 1,5-IP8, strongly decline upon phosphate starvation. Among these, specifically the decline of 1,5-IP8 triggers the transcriptional phosphate starvation response, the PHO pathway. 1,5-IP8 inactivates the cyclin-dependent kinase inhibitor Pho81 through its SPX domain. This stimulates the cyclin-dependent kinase Pho85/Pho80 to phosphorylate the transcription factor Pho4 and repress the PHO pathway. Combining our results with observations from other systems we propose a unified model where 1,5-IP8 signals cytosolic phosphate abundance to SPX proteins in fungi, plants, and mammals. Its absence triggers starvation responses. Cytosolic Pi is of prime importance for cellular bioenergetics because Pi influences free energy of nucleotide hydrolysis and the metabolite fluxes through glycolysis and oxidative phosphorylation. Eukaryotic cells signal Pi via SPX domains binding critical ligands, inositol pyrophosphates (IP7, IP8), which control Pi homeostasis through a network of target proteins that import, export, store or detoxify Pi. Studies with different systems failed to yield a coherent model on this regulation. We performed the first time-resolved profiling of the full isomer spectrum of inositol pyrophosphates and dissected the isomer that is relevant to intracellular Pi signaling. Our results support a unified model of Pi signaling across all eukaryotic kingdoms, which is in accord with the fundamental importance of Pi management for metabolism.

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“…[ 39 – 41 ]. A strong effect of phosphate limitation on glycolysis, early TCA metabolites, such as citric acid, isocitric acid, and oxoglutaric acid, and oxygen consumption has also been reported for Saccharomyces cerevisiae [ 42 ]. The distinct trajectories of the OTR curves under phosphate limitation resemble those previously overserved for Escherichia coli and Hansenula polymorpha [ 43 , 44 ].…”

Section: Resultsmentioning

confidence: 99%

“…On the other hand, Corynebacterium glutamicum was able to maintain its growth rate, when extracellular phosphate was depleted, by reducing the internal phosphate content [ 46 ]. Many species of fungi can store excessive phosphate as polyphosphate in their vacuoles [ 42 , 55 , 56 ]. Under phosphate-limited conditions, the stored polyphosphate is degraded and thus buffers the cytosolic phosphate levels.…”

Section: Resultsmentioning

confidence: 99%

Phosphate limitation enhances malic acid production on nitrogen-rich molasses with Ustilago trichophora

Grebe,

Lichtenberg,

Hürter

et al. 2024

Biotechnol Biofuels

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Background An important step in replacing petrochemical products with sustainable, cost-effective alternatives is the use of feedstocks other than, e.g., pure glucose in the fermentative production of platform chemicals. Ustilaginaceae offer the advantages of a wide substrate spectrum and naturally produce a versatile range of value-added compounds under nitrogen limitation. A promising candidate is the dicarboxylic acid malic acid, which may be applied as an acidulant in the food industry, a chelating agent in pharmaceuticals, or in biobased polymer production. However, fermentable residue streams from the food and agricultural industry with high nitrogen content, e.g., sugar beet molasses, are unsuited for processes with Ustilaginaceae, as they result in low product yields due to high biomass and low product formation. Results This study uncovers challenges in evaluating complex feedstock applicability for microbial production processes, highlighting the role of secondary substrate limitations, internal storage molecules, and incomplete assimilation of these substrates. A microliter-scale screening method with online monitoring of microbial respiration was developed using malic acid production with Ustilago trichophora on molasses as an application example. Investigation into nitrogen, phosphate, sulphate, and magnesium limitations on a defined minimal medium demonstrated successful malic acid production under nitrogen and phosphate limitation. Furthermore, a reduction of nitrogen and phosphate in the elemental composition of U. trichophora was revealed under the respective secondary substrate limitation. These adaptive changes in combination with the intricate metabolic response hinder mathematical prediction of product formation and make the presented screening methodology for complex feedstocks imperative. In the next step, the screening was transferred to a molasses-based complex medium. It was determined that the organism assimilated only 25% and 50% of the elemental nitrogen and phosphorus present in molasses, respectively. Due to the overall low content of bioavailable phosphorus in molasses, the replacement of the state-of-the-art nitrogen limitation was shown to increase malic acid production by 65%. Conclusion The identification of phosphate as a superior secondary substrate limitation for enhanced malic acid production opens up new opportunities for the effective utilization of molasses as a more sustainable and cost-effective substrate than, e.g., pure glucose for biobased platform chemical production.

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Metabolic Consequences of Polyphosphate Synthesis and Imminent Phosphate Limitation

Abstract: Cells must strike a delicate balance between the high demand of inorganic phosphate (P i ) for synthesizing nucleic acids and phospholipids and its detrimental bioenergetic effects by reducing the free energy of nucleotide hydrolysis. The latter may stall metabolism.

Cited by 8 publications

References 118 publications

Promoting Nucleic Acid Synthesis in Saccharomyces cerevisiae through Enhanced Expression of Rrn7p, Rrn11p, IMPDH, and Pho84p

Promoting Nucleic Acid Synthesis in Saccharomyces cerevisiae through Enhanced Expression of Rrn7p, Rrn11p, IMPDH, and Pho84p

Inositol pyrophosphate dynamics reveals control of the yeast phosphate starvation program through 1,5-IP8 and the SPX domain of Pho81

Phosphate limitation enhances malic acid production on nitrogen-rich molasses with Ustilago trichophora

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