A novel role for yeast casein kinases in glucose sensing and signaling

Snowdon, Chris; Johnston, Mark

doi:10.1091/mbc.e16-05-0342

Cited by 31 publications

(40 citation statements)

References 24 publications

(34 reference statements)

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“…The SeYCK1 gene is positioned on Se‐type chromosome XV–VIII. The SeYCK1 gene encodes palmitoylated plasma membrane‐bound casein kinase I and is related to sensing glucose and inducing the expression of hexose transporter genes . As described above, the ScHXK1 and SeYCK1 genes are related to glucose sensing, uptake and metabolism.…”

Section: Discussionmentioning

confidence: 99%

“…We therefore focused on the regulatory mechanisms of glucose uptake in this study. In S. cerevisiae , the transport of hexoses (including glucose) is mediated by the HXT gene products , whose gene expression levels are regulated by a glucose signalling pathway that is triggered by the plasma membrane bound casein kinase I Yck1p and the glucose sensor Rgt2p . Overexpression of YCK1 gene leads to constitutive HXT1 expression, and Yck1p is required for glucose induced expression of the HXT1 gene .…”

Section: Introductionmentioning

confidence: 99%

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Isolation of a lager yeast with an increased copy number of theYCK1gene and high fermentation performance

2018

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The selection of yeast with good fermentation characteristics is critical for producing beer with desirable qualities. A yeast population was selected with an enhanced fermentation rate, referred to as high-fermentation yeast (HFY), which was derived from the wild-type Sacchromyces pastorianus yeast population (WTY). To identify genes that contribute to the fermentation performance, we compared the genetic profiles of the WTY and HFY populations by next-generation sequencing. Several chromosomal regions were found to exhibit markedly different sequence coverage, suggesting chromosomal duplications and deletions, which might have occurred during selection of the HFY population. Among the genes with altered coverage, the copy number of the Saccharomyces eubayanus-type YCK1 (SeYCK1) gene was almost two times higher in the HFY population than in the WTY population. The gene which is involved in glucose sensing in Saccharomyces cerevisiae was at a higher level in the HFY population throughout fermentation. These findings suggest that the chromosomal duplication of a region including the SeYCK1 gene locus of the HFY population is at least partially responsible for the differences in the fermentation properties between the WTY and HFY populations.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Isolation of a lager yeast with an increased copy number of theYCK1gene and high fermentation performance

2018

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“…In the absence of glucose, the regulators Mth1p and Std1p and the transcription factor Rgt1p repress the expression of glucose transporter-encoding genes. The presence of extracellular glucose is sensed by Snf3p and Rgt2p, which subsequently activate casein kinase 1/2 (Yck1/2p), resulting in the phosphorylation and nuclear export of Mth1p and Std1p ( 13 – 19 ). Phosphorylated Mth1p and Std1p are recognized by the SCF ubiquitin-protein ligase complex Grr1p, which targets them for proteasome degradation ( 13 , 15 , 16 , 20 ), whilst Rgt1p is phosphorylated by protein kinase A, thereby relieving the repression of glucose transporter-encoding genes ( 14 , 16 , 21 – 23 ).…”

Section: Introductionmentioning

confidence: 99%

Regulation of Aspergillus nidulans CreA-Mediated Catabolite Repression by the F-Box Proteins Fbx23 and Fbx47

Assis

Ulas

Ries

et al. 2018

mBio

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The attachment of one or more ubiquitin molecules by SCF (Skp–Cullin–F-box) complexes to protein substrates targets them for subsequent degradation by the 26S proteasome, allowing the control of numerous cellular processes. Glucose-mediated signaling and subsequent carbon catabolite repression (CCR) are processes relying on the functional regulation of target proteins, ultimately controlling the utilization of this carbon source. In the filamentous fungus Aspergillus nidulans, CCR is mediated by the transcription factor CreA, which modulates the expression of genes encoding biotechnologically relevant enzymes. Although CreA-mediated repression of target genes has been extensively studied, less is known about the regulatory pathways governing CCR and this work aimed at further unravelling these events. The Fbx23 F-box protein was identified as being involved in CCR and the Δfbx23 mutant presented impaired xylanase production under repressing (glucose) and derepressing (xylan) conditions. Mass spectrometry showed that Fbx23 is part of an SCF ubiquitin ligase complex that is bridged via the GskA protein kinase to the CreA-SsnF-RcoA repressor complex, resulting in the degradation of the latter under derepressing conditions. Upon the addition of glucose, CreA dissociates from the ubiquitin ligase complex and is transported into the nucleus. Furthermore, casein kinase is important for CreA function during glucose signaling, although the exact role of phosphorylation in CCR remains to be determined. In summary, this study unraveled novel mechanistic details underlying CreA-mediated CCR and provided a solid basis for studying additional factors involved in carbon source utilization which could prove useful for biotechnological applications.

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“…Mth1 is abundant only under conditions of no external glucose. External glucose when properly sensed, initiates Mth1 degradation via SCF Grr1 complex mediated ubiquitination and the 26S proteasome which is triggered by Mth1 phosphorylation by Yck1 and Yck2 casein kinases and other unknown factors [ 21 ], [ 22 ], [ 23 ].…”

Section: Introductionmentioning

confidence: 99%

Low RNA Polymerase III activity results in up regulation of HXT2 glucose transporter independently of glucose signaling and despite changing environment

Adamczyk

Szatkowska

2017

PLoS ONE

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BackgroundSaccharomyces cerevisiae responds to glucose availability in the environment, inducing the expression of the low-affinity transporters and high-affinity transporters in a concentration dependent manner. This cellular decision making is controlled through finely tuned communication between multiple glucose sensing pathways including the Snf1-Mig1, Snf3/Rgt2-Rgt1 (SRR) and cAMP-PKA pathways.ResultsWe demonstrate the first evidence that RNA Polymerase III (RNAP III) activity affects the expression of the glucose transporter HXT2 (RNA Polymerase II dependent—RNAP II) at the level of transcription. Down-regulation of RNAP III activity in an rpc128-1007 mutant results in a significant increase in HXT2 mRNA, which is considered to respond only to low extracellular glucose concentrations. HXT2 expression is induced in the mutant regardless of the growth conditions either at high glucose concentration or in the presence of a non-fermentable carbon source such as glycerol. Using chromatin immunoprecipitation (ChIP), we found an increased association of Rgt1 and Tup1 transcription factors with the highly activated HXT2 promoter in the rpc128-1007 strain. Furthermore, by measuring cellular abundance of Mth1 corepressor, we found that in rpc128-1007, HXT2 gene expression was independent from Snf3/Rgt2-Rgt1 (SRR) signaling. The Snf1 protein kinase complex, which needs to be active for the release from glucose repression, also did not appear perturbed in the mutated strain.Conclusions/SignificanceThese findings suggest that the general activity of RNAP III can indirectly affect the RNAP II transcriptional machinery on the HXT2 promoter when cellular perception transduced via the major signaling pathways, broadly recognized as on/off switch essential to either positive or negative HXT gene regulation, remain entirely intact. Further, Rgt1/Ssn6-Tup1 complex, which has a dual function in gene transcription as a repressor-activator complex, contributes to HXT2 transcriptional activation.

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A novel role for yeast casein kinases in glucose sensing and signaling

Abstract: The yeast casein kinases function upstream of the glucose sensors in the sensor/receptor-repressor signaling pathway. The sensor Rgt2 undergoes Yck-dependent phosphorylation on its C-terminal tail, which is necessary for Mth1 and Std1 binding and downstream signaling.

Cited by 31 publications

References 24 publications

Isolation of a lager yeast with an increased copy number of theYCK1gene and high fermentation performance

Isolation of a lager yeast with an increased copy number of theYCK1gene and high fermentation performance

Regulation of Aspergillus nidulans CreA-Mediated Catabolite Repression by the F-Box Proteins Fbx23 and Fbx47

Low RNA Polymerase III activity results in up regulation of HXT2 glucose transporter independently of glucose signaling and despite changing environment

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