Lack of 2'-O-methylation in the tRNA anticodon loop of two phylogenetically distant yeast species activates the general amino acid control pathway

Autor:	Eric M. Phizicky, Michael P. Guy, Lu Han, Yoshiko Kon
Rok vydání:	2018
Předmět:	0301 basic medicine B Vitamins Cancer Research Molecular biology Mutant Gene Expression Yeast and Fungal Models medicine.disease_cause Biochemistry Schizosaccharomyces Pombe RNA Transfer Thiamine Amino Acids Genetics (clinical) Phylogeny 2. Zero hunger Mutation biology Nucleotides Organic Compounds Eukaryota Vitamins Cell biology Nucleic acids Chemistry Experimental Organism Systems Transfer RNA Physical Sciences Research Article lcsh:QH426-470 Saccharomyces cerevisiae Genes Fungal DNA construction Research and Analysis Methods Methylation RNA polymerase III 03 medical and health sciences Saccharomyces Model Organisms Schizosaccharomyces medicine Anticodon Genetics Non-coding RNA Ecology Evolution Behavior and Systematics Organic Chemistry Organisms Fungi Chemical Compounds RNA Biology and Life Sciences biology.organism_classification Yeast lcsh:Genetics 030104 developmental biology Molecular biology techniques Schizosaccharomyces pombe Plasmid Construction Protein Translation Anticodons
Zdroj:	PLoS Genetics PLoS Genetics, Vol 14, Iss 3, p e1007288 (2018)
ISSN:	1553-7404
Popis:	Modification defects in the tRNA anticodon loop often impair yeast growth and cause human disease. In the budding yeast Saccharomyces cerevisiae and the phylogenetically distant fission yeast Schizosaccharomyces pombe, trm7Δ mutants grow poorly due to lack of 2'-O-methylation of C32 and G34 in the tRNAPhe anticodon loop, and lesions in the human TRM7 homolog FTSJ1 cause non-syndromic X-linked intellectual disability (NSXLID). However, it is unclear why trm7Δ mutants grow poorly. We show here that despite the fact that S. cerevisiae trm7Δ mutants had no detectable tRNAPhe charging defect in rich media, the cells constitutively activated a robust general amino acid control (GAAC) response, acting through Gcn2, which senses uncharged tRNA. Consistent with reduced available charged tRNAPhe, the trm7Δ growth defect was suppressed by spontaneous mutations in phenylalanyl-tRNA synthetase (PheRS) or in the pol III negative regulator MAF1, and by overexpression of tRNAPhe, PheRS, or EF-1A; all of these also reduced GAAC activation. Genetic analysis also demonstrated that the trm7Δ growth defect was due to the constitutive robust GAAC activation as well as to the reduced available charged tRNAPhe. Robust GAAC activation was not observed with several other anticodon loop modification mutants. Analysis of S. pombe trm7 mutants led to similar observations. S. pombe Trm7 depletion also resulted in no observable tRNAPhe charging defect and a robust GAAC response, and suppressors mapped to PheRS and reduced GAAC activation. We speculate that GAAC activation is widely conserved in trm7 mutants in eukaryotes, including metazoans, and might play a role in FTSJ1-mediated NSXLID. Author summary The ubiquitous tRNA anticodon loop modifications have important but poorly understood functions in decoding mRNAs in the ribosome to ensure accurate and efficient protein synthesis, and their lack often impairs yeast growth and causes human disease. Here we investigate why ribose methylation of residues 32 and 34 in the anticodon loop is important. Mutations in the corresponding methyltransferase Trm7/FTSJ1 cause poor growth in the budding yeast Saccharomyces cerevisiae and near lethality in the evolutionarily distant fission yeast Schizosaccharomyces pombe, each due to reduced functional tRNAPhe. We previously showed that tRNAPhe anticodon loop modification in yeast and humans required two evolutionarily conserved Trm7 interacting proteins for Cm32 and Gm34 modification, which then stimulated G37 modification. We show here that both S. cerevisiae and S. pombe trm7Δ mutants have apparently normal tRNAPhe charging, but constitutively activate a robust general amino acid control (GAAC) response, acting through Gcn2, which senses uncharged tRNA. We also show that S. cerevisiae trm7Δ mutants grow poorly due in part to constitutive GAAC activation as well as to the uncharged tRNAPhe. We propose that TRM7 is important to prevent constitutive GAAC activation throughout eukaryotes, including metazoans, which may explain non-syndromic X-linked intellectual disability associated with human FTSJ1 mutations.
Databáze:	OpenAIRE
Externí odkaz:	https://explore.openaire.eu/search/publication?articleId=doi_dedup___::1f3d9b9d04fa643c403356642f3a541f https://pubmed.ncbi.nlm.nih.gov/29596413 Zobrazit plný text záznamu Plný text ve formátu PDF Plný text ve formátu HTML
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