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The yeast global transcriptional co-repressor protein Cyc8 can propagate as a prion.

ABSTRACT: Although many proteins can misfold into a self-seeding amyloid-like conformation, only six are known to be infectious, that is prions. The prions [PSI(+)], [PIN(+)], [URE3], [SWI(+)] and [HET-s] cause distinct heritable physiological changes in fungi, whereas PrP(Sc) causes infectious encephalopathies in mammals. It is unknown whether 'protein-only' inheritance is limited to these exceptional cases or whether it represents a widespread mechanism of epigenetic control. Towards this goal, we now describe a new prion formed by the Cyc8 (Ssn6) protein of Saccharomyces cerevisiae. Analogously to other yeast prions, transient overproduction of a glutamine-rich region of Cyc8 induced a heritable dominant cyc8(-) phenotype that is transmitted cytoplasmically and is dependent on the chaperone Hsp104 and the continued presence of the Cyc8 protein. The evolutionarily conserved Cyc8-Tup1 global transcriptional repressor complex forms one of the largest gene regulatory circuits, controlling the expression of more than 7% of yeast genes. Our finding that Cyc8 can propagate as a prion, together with a recent report that Swi1 of the Swi-Snf global transcriptional regulatory complex also has a prion form, shows that prionization can lead to mass activation or repression of yeast genes and is suggestive of a link between the epigenetic phenomena of chromatin remodelling and prion formation.

SUBMITTER: Patel BK

PROVIDER: S-EPMC2667906 | biostudies-literature | 2009 Mar

REPOSITORIES: biostudies-literature

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The yeast global transcriptional co-repressor protein Cyc8 can propagate as a prion.

Patel Basant K BK Gavin-Smyth Jackie J Liebman Susan W SW

Nature cell biology 20090215 3

Although many proteins can misfold into a self-seeding amyloid-like conformation, only six are known to be infectious, that is prions. The prions [PSI(+)], [PIN(+)], [URE3], [SWI(+)] and [HET-s] cause distinct heritable physiological changes in fungi, whereas PrP(Sc) causes infectious encephalopathies in mammals. It is unknown whether 'protein-only' inheritance is limited to these exceptional cases or whether it represents a widespread mechanism of epigenetic control. Towards this goal, we now d ...[more]

PMID: 19219034

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Project description:The yeast Xanthophyllomyces dendrorhous produces carotenoids of commercial interest, including astaxanthin and ?-carotene. Although carotenogenesis in this yeast and the expression profiles of the genes controlling this pathway are known, the mechanisms regulating this process remain poorly understood. Several studies have demonstrated that glucose represses carotenogenesis in X. dendrorhous, suggesting that this pathway could be regulated by catabolic repression. Catabolic repression is a highly conserved regulatory mechanism in eukaryotes and has been widely studied in Saccharomyces cerevisiae. Glucose-dependent repression is mainly observed at the transcriptional level and depends on the DNA-binding regulator Mig1, which recruits the co-repressor complex Cyc8-Tup1, which then represses the expression of target genes. In this work, we studied the regulation of carotenogenesis by catabolic repression in X. dendrorhous, focusing on the role of the co-repressor complex Cyc8-Tup1.The X. dendrorhous CYC8 and TUP1 genes were identified, and their functions were demonstrated by heterologous complementation in S. cerevisiae. In addition, cyc8 - and tup1 - mutant strains of X. dendrorhous were obtained, and both mutations were shown to prevent the glucose-dependent repression of carotenogenesis in X. dendrorhous, increasing the carotenoid production in both mutant strains. Furthermore, the effects of glucose on the transcript levels of genes involved in carotenogenesis differed between the mutant strains and wild-type X. dendrorhous, particularly for genes involved in the synthesis of carotenoid precursors, such as HMGR, idi and FPS. Additionally, transcriptomic analyses showed that cyc8 - and tup1 - mutations affected the expression of over 250 genes in X. dendrorhous.The CYC8 and TUP1 genes are functional in X. dendrorhous, and their gene products are involved in catabolic repression and carotenogenesis regulation. This study presents the first report involving the participation of Cyc8 and Tup1 in carotenogenesis regulation in yeast.

Dataset Information

The yeast global transcriptional co-repressor protein Cyc8 can propagate as a prion.

Publications

The yeast global transcriptional co-repressor protein Cyc8 can propagate as a prion.

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