Effects of MCHM on yeast metabolism

Pupo, Amaury; Ku, Kang‐Mo; Gallagher, Jennifer E. G.

doi:10.1101/609800

Cited by 2 publications

(1 citation statement)

References 66 publications

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“…These types of hydrotropes act to concentrate compounds. Exposure to MCHM induced growth arrest in yeast by changing a wide range of biochemical pathways including ionome (22) and amino acids (27). The Mediator binds upstream of many genes across pathways, including stress responsive genes.…”

Section: Introductionmentioning

confidence: 99%

The polymorphic PolyQ tail protein of the Mediator Complex, Med15, regulates variable response to stress

Gallagher

Nassif

Pupo

2019

Preprint

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The Mediator is a multi-protein complex composed of subunits called head, body, tail, and CDK that is conserved from yeast to humans and plays a central role in transcription. However, not all the components are required for basal transcription. Components of the tail are not essential but to varying degrees are required for growth in different stresses. While some stresses are familiar such as heat, desiccation, and starvation, others are exotic, yet yeast can elicit a successful stress response. MCHM is a hydrotrope that induces growth arrest in yeast. By exploiting genetic variation, specifically in Med15, between yeast strains, we found that a naturally occurring Med15 allele with polyQ (polyglutamine) expansion conferred MCHM sensitivity. Expansion in polyQ repeat can induce protein aggregation and in humans can cause neurodegenerative diseases. In yeast, the MCHM sensitivity was not from a loss of function as the reciprocal hemizygous hybrids were all sensitive and the homozygous null mutant was less sensitive than the hemizygous hybrids. This suggests that there is an incompatibility between Mediator components from genetic divergent yeast strains. Transcriptomics from yeast expressing the incompatible Med15 (longer polyQ repeats in the strain with fewer repeats) changed gene expression in diverse pathways. Med15 protein existed in multiple isoforms, mostly from likely post-translational modifications and different alleles have different patterns of isoforms. Stability of both alleles of Med15 was dependent on Ydj1, a J-type chaperone. The protein level of the incompatible Med15 allele was lower than the compatible allele and was turned over faster. Med15 is tethered to the rest of the Mediator complex via Med2 and 3. Deletion of either Med2 or Med3 changed the Med15 isoform patterns in a similar manner. Whereas deletion of Med5, a distal component of the Mediator tail, did not change the pattern. The med2 and med3 mutants were similarly sensitive to MCHM while med5 mutants were not. Differences in the phenotype of yeast carrying different Med15 alleles extend to other stresses. The incompatible allele of Med15 improved growth of yeast to chemicals that produce free radicals and the compatible allele of Med15 improved growth to reducing agents, caffeine, and hydroxyurea. Med15 directly interacts with Gcn4 and other TFs and in vitro form phaseseparated droplets. This variation may reflect the positive and negative role that Med15 has in transcription. Genetic variation in transcriptional regulators can magnify differences in response to environmental changes, in contrast, genetic variation in a metabolic enzyme. These polymorphic control genes are master variators.

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Section: Introductionmentioning

confidence: 99%

The polymorphic PolyQ tail protein of the Mediator Complex, Med15, regulates variable response to stress

Gallagher

Nassif

Pupo

2019

Preprint

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The Polymorphic PolyQ Tail Protein of the Mediator Complex, Med15, Regulates the Variable Response to Diverse Stresses

Jeg

Ayers

et al. 2020

IJMS

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The Mediator is composed of multiple subunits conserved from yeast to humans and plays a central role in transcription. The tail components are not required for basal transcription but are required for responses to different stresses. While some stresses are familiar, such as heat, desiccation, and starvation, others are exotic, yet yeast can elicit a successful stress response. 4-Methylcyclohexane methanol (MCHM) is a hydrotrope that induces growth arrest in yeast. We found that a naturally occurring variation in the Med15 allele, a component of the Mediator tail, altered the stress response to many chemicals in addition to MCHM. Med15 contains two polyglutamine repeats (polyQ) of variable lengths that change the gene expression of diverse pathways. The Med15 protein existed in multiple isoforms and its stability was dependent on Ydj1, a protein chaperone. The protein level of Med15 with longer polyQ tracts was lower and turned over faster than the allele with shorter polyQ repeats. MCHM sensitivity via variation of Med15 was regulated by Snf1 in a Myc-tag-dependent manner. Tagging Med15 with Myc altered its function in response to stress. Genetic variation in transcriptional regulators magnified genetic differences in response to environmental changes. These polymorphic control genes were master variators.

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Effects of MCHM on yeast metabolism

Cited by 2 publications

References 66 publications

The polymorphic PolyQ tail protein of the Mediator Complex, Med15, regulates variable response to stress

The polymorphic PolyQ tail protein of the Mediator Complex, Med15, regulates variable response to stress

The Polymorphic PolyQ Tail Protein of the Mediator Complex, Med15, Regulates the Variable Response to Diverse Stresses

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