Single point mutations in Met4p impair the transcriptional repression of <i>MET</i> genes in <i>Saccharomyces cerevisiae</i>

Omura, Fumihiko; Fujita, Atsushi; Shibano, Yuji

doi:10.1016/0014-5793(96)00486-3

Cited by 6 publications

(7 citation statements)

References 19 publications

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“…However, several lines of evidence suggested that down‐regulation of Met4 activity could not explain the methionine‐mediated growth inhibition of map1Δ . First, expression of a dominant mutant of Met4, which is non‐responsive to methionine inhibition [Omura et al, 1996], was unable to overcome growth inhibition by methionine (data not shown). Secondly, addition of SAM, a methionine metabolite that is a more proximal mediator of MET gene repression than methionine [Thomas and Surdin‐Kerjan, 1997], did not inhibit the growth of map1Δ (Table II).…”

Section: Resultsmentioning

confidence: 99%

N‐terminal methionine removal and methionine metabolism in Saccharomyces cerevisiae

Dummitt¹,

Micka²,

Chang³

2003

J of Cellular Biochemistry

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Methionine aminopeptidase (MetAP) catalyzes removal of the initiator methionine from nascent polypeptides. In eukaryotes, there are two forms of MetAP, type 1 and type 2, whose combined activities are essential, but whose relative intracellular roles are unclear. Methionine metabolism is an important aspect of cellular physiology, involved in oxidative stress, methylation, and cell cycle. Due to the potential of MetAP activity to provide a methionine salvage pathway, we evaluated the relationship between methionine metabolism and MetAP activity in Saccharomyces cerevisiae. We provide the first demonstration that yeast MetAP1 plays a significant role in methionine metabolism, namely, preventing premature activation of MET genes through MetAP function in methionine salvage. Interestingly, in cells lacking MetAP1, excess methionine dramatically inhibits cell growth. Growth inhibition is independent of the ability of methionine to repress MET genes and does not result from inhibition of synthesis of another metabolite, rather it results from product inhibition of MetAP2. Inhibition by methionine is selective for MetAP2 over MetAP1. These results provide an explanation for the previously observed dominance of MetAP1 in terms of N-terminal processing and cell growth in yeast. Additionally, differential regulation of the two isoforms may be indicative of different intracellular roles for the two enzymes.

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Section: Resultsmentioning

confidence: 99%

N‐terminal methionine removal and methionine metabolism in Saccharomyces cerevisiae

Dummitt¹,

Micka²,

Chang³

2003

J of Cellular Biochemistry

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“…We had previously mapped the IR domain as a region of Met4–Met30 protein interaction by two‐hybrid analysis (Thomas et al ., 1995); however, our IR deletion mutant was unable to induce lethality in the presence of Met30p. This suggested that the Met4 IR domain may include amino acid residues outside of 189–235, consistent with data reported by Omura and colleagues, who isolated a Met4p point mutant (F156S) that was unresponsive to high extracellular methionine (Omura et al ., 1996). We thus constructed a new set of deletions around the IR region of GAL1–MET4 and expressed them in met4Δ MET30 cells.…”

Section: Resultsmentioning

confidence: 99%

“…The essential function of Met30p is required for passage through G 1 phase data reported by Omura and colleagues, who isolated a Met4p point mutant (F156S) that was unresponsive to Conditional expression of the MET4 gene from a GAL1 promoter in met4Δ met30Δ double mutants allowed us high extracellular methionine (Omura et al, 1996). We thus constructed a new set of deletions around the IR to characterize the phenotype of met30Δ mutants.…”

Section: Genotypementioning

confidence: 96%

SCFMet30-mediated control of the transcriptional activator Met4 is required for the G1-S transition

Patton

2000

The EMBO Journal

124

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Progression through the cell cycle requires the coordination of basal metabolism with the cell cycle and growth machinery. Repression of the sulfur gene network is mediated by the ubiquitin ligase SCFMet30, which targets the transcription factor Met4p for degradation. Met30p is an essential protein in yeast. We have found that a met4Δmet30Δ double mutant is viable, suggesting that the essential function of Met30p is to control Met4p. In support of this hypothesis, a Met4p mutant unable to activate transcription does not cause inviability in a met30Δ strain. Also, overexpression of an unregulated Met4p mutant is lethal in wild‐type cells. Under non‐permissive conditions, conditional met30Δ strains arrest as large, unbudded cells with 1N DNA content, at or shortly after the pheromone arrest point. met30Δ conditional mutants fail to accumulate CLN1 and CLN2, but not CLN3 mRNAs, even when CLN1 and CLN2 are expressed from strong heterologous promoters. One or more genes under the regulation of Met4p may delay the progression from G1 into S phase through specific regulation of critical G1 phase mRNAs.

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“…The monomers do not re-dimerize spontaneously in the absence of the cofactors, suggesting that a major, not easily reversible change in Met4 structure accompanies its monomerization by SCF Met30 . That a major structural change accompanies Met4 activation has been independently proposed based on genetic analysis of the constitutively active Met4-1 and Met4-2 mutants, which display a dominant negative phenotype in the presence of wild type Met4 [ 31 ].…”

Section: Reviewmentioning

confidence: 99%

“…In this view, turnover of Met4 protein would be an integral part of its function, with only a fraction of the total cellular Met4 degraded at a time, balancing the constitutive expression of the MET4 gene (Fig. 3A ; [ 9 , 31 ]).…”

Section: Reviewmentioning

confidence: 99%

The emerging regulatory potential of SCFMet30 -mediated polyubiquitination and proteolysis of the Met4 transcriptional activator

Chandrasekaran

Skowyra

2008

Cell Div

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The yeast SCF Met30 ubiquitin ligase plays a critical role in cell division by regulating the Met4 transcriptional activator of genes that control the uptake and assimilation of sulfur into methionine and S-adenosyl-methionine. The initial view on how SCF Met30 performs its function has been driven by the assumption that SCF Met30 acts exclusively as Met4 inhibitor when high levels of methionine drive an accumulation of cysteine. We revisit this model in light of the growing evidence that SCF Met30 can also activate Met4. The notion that Met4 can be inhibited or activated depending on the sulfur metabolite context is not new, but for the first time both aspects have been linked to SCF Met30 , creating an interesting regulatory paradigm in which polyubiquitination and proteolysis of a single transcriptional activator can play different roles depending on context. We discuss the emerging molecular basis and the implications of this new regulatory phenomenon.

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Single point mutations in Met4p impair the transcriptional repression of MET genes in Saccharomyces cerevisiae

Cited by 6 publications

References 19 publications

N‐terminal methionine removal and methionine metabolism in Saccharomyces cerevisiae

N‐terminal methionine removal and methionine metabolism in Saccharomyces cerevisiae

SCFMet30-mediated control of the transcriptional activator Met4 is required for the G1-S transition

The emerging regulatory potential of SCFMet30 -mediated polyubiquitination and proteolysis of the Met4 transcriptional activator

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