Aberrant Intracellular pH Regulation Limiting Glyceraldehyde-3-Phosphate Dehydrogenase Activity in the Glucose-Sensitive Yeast <italic toggle="yes">tps1</italic>Δ Mutant

ABSTRACT Whereas the yeast Saccharomyces cerevisiae shows great preference for glucose as a carbon source, a deletion mutant in trehalose-6-phosphate synthase, tps1Δ, is highly sensitive to even a few millimolar glucose, which triggers apoptosis and cell death. Glucose addition to tps1Δ cells causes...

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Autores principales:	Frederik Van Leemputte, Ward Vanthienen, Stefanie Wijnants, Griet Van Zeebroeck, Johan M. Thevelein
Formato:	article
Lenguaje:	EN
Publicado:	American Society for Microbiology 2020
Materias:	glycolysis intracellular pH glyceraldehyde-3-phosphate dehydrogenase trehalose-6-phosphate synthase Saccharomyces cerevisiae glucose metabolism Microbiology QR1-502
Acceso en línea:	https://doaj.org/article/a635266183c74eef89fb5533e010461d
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spelling	oai:doaj.org-article:a635266183c74eef89fb5533e010461d2021-11-15T16:19:08ZAberrant Intracellular pH Regulation Limiting Glyceraldehyde-3-Phosphate Dehydrogenase Activity in the Glucose-Sensitive Yeast <italic toggle="yes">tps1</italic>Δ Mutant10.1128/mBio.02199-202150-7511https://doaj.org/article/a635266183c74eef89fb5533e010461d2020-10-01T00:00:00Zhttps://journals.asm.org/doi/10.1128/mBio.02199-20https://doaj.org/toc/2150-7511ABSTRACT Whereas the yeast Saccharomyces cerevisiae shows great preference for glucose as a carbon source, a deletion mutant in trehalose-6-phosphate synthase, tps1Δ, is highly sensitive to even a few millimolar glucose, which triggers apoptosis and cell death. Glucose addition to tps1Δ cells causes deregulation of glycolysis with hyperaccumulation of metabolites upstream and depletion downstream of glyceraldehyde-3-phosphate dehydrogenase (GAPDH). The apparent metabolic barrier at the level of GAPDH has been difficult to explain. We show that GAPDH isozyme deletion, especially Tdh3, further aggravates glucose sensitivity and metabolic deregulation of tps1Δ cells, but overexpression does not rescue glucose sensitivity. GAPDH has an unusually high pH optimum of 8.0 to 8.5, which is not altered by tps1Δ. Whereas glucose causes short, transient intracellular acidification in wild-type cells, in tps1Δ cells, it causes permanent intracellular acidification. The hxk2Δ and snf1Δ suppressors of tps1Δ restore the transient acidification. These results suggest that GAPDH activity in the tps1Δ mutant may be compromised by the persistently low intracellular pH. Addition of NH4Cl together with glucose at high extracellular pH to tps1Δ cells abolishes the pH drop and reduces glucose-6-phosphate (Glu6P) and fructose-1,6-bisphosphate (Fru1,6bisP) hyperaccumulation. It also reduces the glucose uptake rate, but a similar reduction in glucose uptake rate in a tps1Δ hxt2,4,5,6,7Δ strain does not prevent glucose sensitivity and Fru1,6bisP hyperaccumulation. Hence, our results suggest that the glucose-induced intracellular acidification in tps1Δ cells may explain, at least in part, the apparent glycolytic bottleneck at GAPDH but does not appear to fully explain the extreme glucose sensitivity of the tps1Δ mutant. IMPORTANCE Glucose catabolism is the backbone of metabolism in most organisms. In spite of numerous studies and extensive knowledge, major controls on glycolysis and its connections to the other metabolic pathways remain to be discovered. A striking example is provided by the extreme glucose sensitivity of the yeast tps1Δ mutant, which undergoes apoptosis in the presence of just a few millimolar glucose. Previous work has shown that the conspicuous glucose-induced hyperaccumulation of the glycolytic metabolite fructose-1,6-bisphosphate (Fru1,6bisP) in tps1Δ cells triggers apoptosis through activation of the Ras-cAMP-protein kinase A (PKA) signaling pathway. However, the molecular cause of this Fru1,6bisP hyperaccumulation has remained unclear. We now provide evidence that the persistent drop in intracellular pH upon glucose addition to tps1Δ cells likely compromises the activity of glyceraldehyde-3-phosphate dehydrogenase (GAPDH), a major glycolytic enzyme downstream of Fru1,6bisP, due to its unusually high pH optimum. Our work highlights the potential importance of intracellular pH fluctuations for control of major metabolic pathways.Frederik Van LeemputteWard VanthienenStefanie WijnantsGriet Van ZeebroeckJohan M. TheveleinAmerican Society for Microbiologyarticleglycolysisintracellular pHglyceraldehyde-3-phosphate dehydrogenasetrehalose-6-phosphate synthaseSaccharomyces cerevisiaeglucose metabolismMicrobiologyQR1-502ENmBio, Vol 11, Iss 5 (2020)
institution	DOAJ
collection	DOAJ
language	EN
topic	glycolysis intracellular pH glyceraldehyde-3-phosphate dehydrogenase trehalose-6-phosphate synthase Saccharomyces cerevisiae glucose metabolism Microbiology QR1-502
spellingShingle	glycolysis intracellular pH glyceraldehyde-3-phosphate dehydrogenase trehalose-6-phosphate synthase Saccharomyces cerevisiae glucose metabolism Microbiology QR1-502 Frederik Van Leemputte Ward Vanthienen Stefanie Wijnants Griet Van Zeebroeck Johan M. Thevelein Aberrant Intracellular pH Regulation Limiting Glyceraldehyde-3-Phosphate Dehydrogenase Activity in the Glucose-Sensitive Yeast <italic toggle="yes">tps1</italic>Δ Mutant
description	ABSTRACT Whereas the yeast Saccharomyces cerevisiae shows great preference for glucose as a carbon source, a deletion mutant in trehalose-6-phosphate synthase, tps1Δ, is highly sensitive to even a few millimolar glucose, which triggers apoptosis and cell death. Glucose addition to tps1Δ cells causes deregulation of glycolysis with hyperaccumulation of metabolites upstream and depletion downstream of glyceraldehyde-3-phosphate dehydrogenase (GAPDH). The apparent metabolic barrier at the level of GAPDH has been difficult to explain. We show that GAPDH isozyme deletion, especially Tdh3, further aggravates glucose sensitivity and metabolic deregulation of tps1Δ cells, but overexpression does not rescue glucose sensitivity. GAPDH has an unusually high pH optimum of 8.0 to 8.5, which is not altered by tps1Δ. Whereas glucose causes short, transient intracellular acidification in wild-type cells, in tps1Δ cells, it causes permanent intracellular acidification. The hxk2Δ and snf1Δ suppressors of tps1Δ restore the transient acidification. These results suggest that GAPDH activity in the tps1Δ mutant may be compromised by the persistently low intracellular pH. Addition of NH4Cl together with glucose at high extracellular pH to tps1Δ cells abolishes the pH drop and reduces glucose-6-phosphate (Glu6P) and fructose-1,6-bisphosphate (Fru1,6bisP) hyperaccumulation. It also reduces the glucose uptake rate, but a similar reduction in glucose uptake rate in a tps1Δ hxt2,4,5,6,7Δ strain does not prevent glucose sensitivity and Fru1,6bisP hyperaccumulation. Hence, our results suggest that the glucose-induced intracellular acidification in tps1Δ cells may explain, at least in part, the apparent glycolytic bottleneck at GAPDH but does not appear to fully explain the extreme glucose sensitivity of the tps1Δ mutant. IMPORTANCE Glucose catabolism is the backbone of metabolism in most organisms. In spite of numerous studies and extensive knowledge, major controls on glycolysis and its connections to the other metabolic pathways remain to be discovered. A striking example is provided by the extreme glucose sensitivity of the yeast tps1Δ mutant, which undergoes apoptosis in the presence of just a few millimolar glucose. Previous work has shown that the conspicuous glucose-induced hyperaccumulation of the glycolytic metabolite fructose-1,6-bisphosphate (Fru1,6bisP) in tps1Δ cells triggers apoptosis through activation of the Ras-cAMP-protein kinase A (PKA) signaling pathway. However, the molecular cause of this Fru1,6bisP hyperaccumulation has remained unclear. We now provide evidence that the persistent drop in intracellular pH upon glucose addition to tps1Δ cells likely compromises the activity of glyceraldehyde-3-phosphate dehydrogenase (GAPDH), a major glycolytic enzyme downstream of Fru1,6bisP, due to its unusually high pH optimum. Our work highlights the potential importance of intracellular pH fluctuations for control of major metabolic pathways.
format	article
author	Frederik Van Leemputte Ward Vanthienen Stefanie Wijnants Griet Van Zeebroeck Johan M. Thevelein
author_facet	Frederik Van Leemputte Ward Vanthienen Stefanie Wijnants Griet Van Zeebroeck Johan M. Thevelein
author_sort	Frederik Van Leemputte
title	Aberrant Intracellular pH Regulation Limiting Glyceraldehyde-3-Phosphate Dehydrogenase Activity in the Glucose-Sensitive Yeast <italic toggle="yes">tps1</italic>Δ Mutant
title_short	Aberrant Intracellular pH Regulation Limiting Glyceraldehyde-3-Phosphate Dehydrogenase Activity in the Glucose-Sensitive Yeast <italic toggle="yes">tps1</italic>Δ Mutant
title_full	Aberrant Intracellular pH Regulation Limiting Glyceraldehyde-3-Phosphate Dehydrogenase Activity in the Glucose-Sensitive Yeast <italic toggle="yes">tps1</italic>Δ Mutant
title_fullStr	Aberrant Intracellular pH Regulation Limiting Glyceraldehyde-3-Phosphate Dehydrogenase Activity in the Glucose-Sensitive Yeast <italic toggle="yes">tps1</italic>Δ Mutant
title_full_unstemmed	Aberrant Intracellular pH Regulation Limiting Glyceraldehyde-3-Phosphate Dehydrogenase Activity in the Glucose-Sensitive Yeast <italic toggle="yes">tps1</italic>Δ Mutant
title_sort	aberrant intracellular ph regulation limiting glyceraldehyde-3-phosphate dehydrogenase activity in the glucose-sensitive yeast <italic toggle="yes">tps1</italic>δ mutant
publisher	American Society for Microbiology
publishDate	2020
url	https://doaj.org/article/a635266183c74eef89fb5533e010461d
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Aberrant Intracellular pH Regulation Limiting Glyceraldehyde-3-Phosphate Dehydrogenase Activity in the Glucose-Sensitive Yeast <italic toggle="yes">tps1</italic>Δ Mutant

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