Activation of the Hog1 <scp>MAPK</scp> by the Ssk2/Ssk22 <scp>MAP</scp>3Ks, in the absence of the osmosensors, is not sufficient to trigger osmostress adaptation in <i>Saccharomyces cerevisiae</i>

Vázquez-Ibarra, Araceli; Subirana, Laia; Ongay‐Larios, Laura; Kawasaki, Laura; Rojas-Ortega, Eréndira; Rodríguez-González, Miriam; Nadal, Eulàlia de; Posas, Francesc; Coria, Roberto

doi:10.1111/febs.14385

Cited by 10 publications

(7 citation statements)

References 64 publications

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“…Osmostress can activate the Hog1 MAPK in the absence of the upstream osmosensors Several studies have reported that Hog1 can be activated at very high osmolarity (> 1 M NaCl) in strains that are defective in both the SLN1 and SHO1 branches, such as ssk1D ste11D and ssk2/22D sho1D (Van Wuytswinkel et al, 2000;O'Rourke & Herskowitz, 2004;Zhi et al, 2013;Vázquez-Ibarra et al, 2019). Since each of the strains used in those studies expressed at least one MAP3K in the HOG pathway (Ssk2, Ssk22, or Ste11), the results were interpreted as evidence for an alternative mechanism for MAP3K activation following osmostress.…”

Section: Resultsmentioning

confidence: 99%

Osmostress enhances activating phosphorylation of Hog1 MAP kinase by mono‐phosphorylated Pbs2 MAP 2K

et al. 2020

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The MAP kinase (MAPK) Hog1 is the central regulator of osmoadaptation in yeast. When cells are exposed to high osmolarity, the functionally redundant Sho1 and Sln1 osmosensors, respectively, activate the Ste11‐Pbs2‐Hog1 MAPK cascade and the Ssk2/Ssk22‐Pbs2‐Hog1 MAPK cascade. In a canonical MAPK cascade, a MAPK kinase kinase (MAP3K) activates a MAPK kinase (MAP2K) by phosphorylating two conserved Ser/Thr residues in the activation loop. Here, we report that the MAP3K Ste11 phosphorylates only one activating phosphorylation site (Thr‐518) in Pbs2, whereas the MAP3Ks Ssk2/Ssk22 can phosphorylate both Ser‐514 and Thr‐518 under optimal osmostress conditions. Mono‐phosphorylated Pbs2 cannot phosphorylate Hog1 unless the reaction between Pbs2 and Hog1 is enhanced by osmostress. The lack of the osmotic enhancement of the Pbs2‐Hog1 reaction suppresses Hog1 activation by basal MAP3K activities and prevents pheromone‐to‐Hog1 crosstalk in the absence of osmostress. We also report that the rapid‐and‐transient Hog1 activation kinetics at mildly high osmolarities and the slow and prolonged activation kinetics at severely high osmolarities are both caused by a common feedback mechanism.

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Section: Resultsmentioning

confidence: 99%

Osmostress enhances activating phosphorylation of Hog1 MAP kinase by mono‐phosphorylated Pbs2 MAP 2K

et al. 2020

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“…Figure 4 Engineering xylose metabolism in yeasts to produce Biofuel: Xylose assimilation pathway followed by Oxidative and Non-oxidative Pentose Phosphate Pathway [35] In the process of yeast xylose metabolism, xylose is transformed into xylulose through the process of isomerization, which occurs under aerobic conditions [34]. Two distinct routes -the oxidoreductase pathway and the isomerase pathway, are used by xylose-fermenting bacteria to transform xylose into xylulose [34]. However, xylose-fermenting yeasts utilize the oxidoreductase pathway, which consists of two enzymatic reactions [34].…”

Section: Modified Xylose Metabolismmentioning

confidence: 99%

“…Two distinct routes -the oxidoreductase pathway and the isomerase pathway, are used by xylose-fermenting bacteria to transform xylose into xylulose [34]. However, xylose-fermenting yeasts utilize the oxidoreductase pathway, which consists of two enzymatic reactions [34].…”

Section: Modified Xylose Metabolismmentioning

confidence: 99%

Improvement of Large-Scale Production of Lignocellulosic Bioethanol through Synthetic Biology Approaches: A Comprehensive Review

Roy¹,

Manna²,

Chowdhury³

et al. 2023

World J. Bio. Pharm. Health Sci.

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This review article explores the use of synthetic biology approaches like gene editing and metabolic engineering to create genetically-modified organisms that can produce commercially-valuable products on large-scale, clean environmental pollutants, and serve as efficient biosensors. The Biobrick system includes a registry of available genetic information and a set of standard protocols for assembling and testing them, which finds various significant uses in synthetic biology, such as in the production of "Fourth generation” biofuel. Genetic engineering techniques may be applied to manipulate crops or microbes for more efficient biofuel production. Such synthetic biology techniques also include modification of lignin structure and content, use of bacterial enzymes abundantly expressed in plants, and manipulation of hemicellulose biosynthesis. However, challenges such as high temperature, efficient conversion of all substrate molecules for maximum product yield, efficient pentose fermentation, and tolerance to acetic acid and bioethanol concentration can all impact the yield of the product. This article explores innovative genetic modification approaches designed to decrease lignin levels and enhance crop digestibility in plants, with a specific focus on the model plant Arabidopsis thaliana and herbaceous plants such as Alfalfa. The aim is to manipulate the Monolignol pathway and modify the CSE gene, known for its ability to decrease lignin content. These modifications have been shown to significantly improve saccharification efficiency and increase the yield of lignocellulosic bioethanol. Besides, the role of xylulose-5-phosphate as an intermediate in the non-oxidative pentose phosphate pathway and the oxidative pentose phosphate pathway, and the use of heterologous xylose transporters and modified sugar transporters as potential solutions to improve the biofuel production efficiency is also discussed in this review article.

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“…Some reports indicate that Hog1 may be activated by an alternative mechanism to the known sensors of the Sho1 and Sln1 branches, and that Ssk2 could be activated by an alternative route as an additional input for Hog1 phosphorylation under severe hyperosmotic stress [47,48]. However, phosphorylation of this MAPK in the absence of the known sensors of both branches fails to induce a protective response due to a diminished transcription activity of hyperosmolarity-responsive genes and defects in cell cycle regulation [49]. It is therefore tempting to speculate that one of the main roles of this alternative pathway could be to feed the CWI pathway.…”

Section: The Mkks and Mapks Of The Hog And Cwi Pathways Form A Proteimentioning

confidence: 99%

Rewiring the yeast cell wall integrity (CWI) pathway through a synthetic positive feedback circuit unveils a novel role for the MAPKKK Ssk2 in CWI pathway activation

et al. 2020

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The cell wall integrity (CWI) pathway mediates the response of Saccharomyces cerevisiae to cell wall alterations. Stress at the cell surface is detected by mechanosensors, which transduce the signal to a protein kinase cascade that involves Pkc1, Bck1, Mkk1/Mkk2, the mitogen-activated protein kinase (MAPK) Slt2 and the transcription factor Rlm1. We incorporated a positive feedback loop into this pathway by placing a hyperactive MKK1 allele under the control of the Rlm1-regulated MLP1 promoter. This circuit operates as a signal amplifier and leads to a highly increased Slt2 activation under stimulating conditions. Triggering the CWI pathway in cells engineered with this circuit, which we have named the Integrity Pathway Activation Circuit (IPAC), results in strong growth inhibition. Exploitation of this hypersensitive phenotype allowed the identification of novel proteins that contribute in signalling to Rlm1 in response to cell surface stressing agents such as Congo red, zymolyase and SDS. Among these proteins, the MAPK kinase kinase Ssk2 of the osmoregulatory high-osmolarity glycerol (HOG) pathway, but not its paralogue Ssk22, proved to be necessary for the SDS-induced IPAC-mediated growth inhibition. We found the existence of an Ssk1-independent Ssk2-Pbs2-Hog1-CWI pathway signalling axis that contributes to Slt2 activation in response to cell surface stress. We also demonstrated that the MAP kinase kinases Mkk1 and Pbs2 and the MAPKs Slt2 and Hog1 of the HOG and CWI pathways interact physically, forming a complex. Our results show how a simple synthetic circuit can be used as a powerful tool for a better understanding of signalling pathways.

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Activation of the Hog1 MAPK by the Ssk2/Ssk22 MAP3Ks, in the absence of the osmosensors, is not sufficient to trigger osmostress adaptation in Saccharomyces cerevisiae

Cited by 10 publications

References 64 publications

Osmostress enhances activating phosphorylation of Hog1 MAP kinase by mono‐phosphorylated Pbs2 MAP 2K

Osmostress enhances activating phosphorylation of Hog1 MAP kinase by mono‐phosphorylated Pbs2 MAP 2K

Improvement of Large-Scale Production of Lignocellulosic Bioethanol through Synthetic Biology Approaches: A Comprehensive Review

Rewiring the yeast cell wall integrity (CWI) pathway through a synthetic positive feedback circuit unveils a novel role for the MAPKKK Ssk2 in CWI pathway activation

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