A genetic screen for suppressors of hyper-repression of the fission yeast PHO regulon by Pol2 CTD mutation T4A implicates inositol 1-pyrophosphates as agonists of precocious lncRNA transcription termination
| Autor: | Beate Schwer, Angad Garg, Stewart Shuman |
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| Rok vydání: | 2020 |
| Předmět: |
AcademicSubjects/SCI00010
Inositol Phosphates Acid Phosphatase RNA polymerase II Biology Regulon Transcription (biology) Catalytic Domain Gene Expression Regulation Fungal Schizosaccharomyces Gene expression Genetics Pyrophosphatases Gene Gene regulation Chromatin and Epigenetics Promoter DNA Polymerase II Multifunctional Enzymes Up-Regulation Cell biology Cytoskeletal Proteins Transcription Termination Genetic Mutation biology.protein RNA Long Noncoding Schizosaccharomyces pombe Proteins Synthetic Lethal Mutations Genetic screen |
| Zdroj: | Nucleic Acids Research |
| ISSN: | 1362-4962 0305-1048 |
| Popis: | Fission yeast phosphate homeostasis genes are repressed in phosphate-rich medium by transcription of upstream lncRNAs that interferes with activation of the flanking mRNA promoters. lncRNA control of PHO gene expression is influenced by the Thr4 phospho-site in the RNA polymerase II CTD and the 3′ processing/termination factors CPF and Rhn1, mutations of which result in hyper-repression of the PHO regulon. Here, we performed a forward genetic screen for mutations that de-repress Pho1 acid phosphatase expression in CTD-T4A cells. Sequencing of 18 independent STF (Suppressor of Threonine Four) isolates revealed, in every case, a mutation in the C-terminal pyrophosphatase domain of Asp1, a bifunctional inositol pyrophosphate (IPP) kinase/pyrophosphatase that interconverts 5-IP7 and 1,5-IP8. Focused characterization of two STF strains identified 51 coding genes coordinately upregulated vis-à-vis the parental T4A strain, including all three PHO regulon genes (pho1, pho84, tgp1). Whereas these STF alleles—asp1-386(Stop) and asp1-493(Stop)—were lethal in a wild-type CTD background, they were viable in combination with mutations in CPF and Rhn1, in which context Pho1 was also de-repressed. Our findings implicate Asp1 pyrophosphatase in constraining 1,5-IP8 or 1-IP7 synthesis by Asp1 kinase, without which 1-IPPs can accumulate to toxic levels that elicit precocious termination by CPF/Rhn1. |
| Databáze: | OpenAIRE |
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