Up-regulation of tRNA biosynthesis affects translational readthrough in maf1- Δ mutant of Saccharomyces cerevisiae

Kwapisz, Marta; Smagowicz, Wiesław J.; Oficjalska, Danuta; Hatin, Isabelle; Rousset, Jean‐Pierre; Żołądek, Teresa; Boguta, Magdalena

doi:10.1007/s00294-002-0342-7

Cited by 27 publications

(20 citation statements)

References 22 publications

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“…A potential source of differing rates might be the species-specific composition of the tRNA gene complement (tRNAome) (16). Consistent with this possibility are mutants in Maf1, a repressor of tRNA synthesis, that exhibit asymmetric increases in the levels of different tRNAs and increased translational fidelity at UAA and UAG codons (17).…”

mentioning

confidence: 86%

Lack of tRNA Modification Isopentenyl-A37 Alters mRNA Decoding and Causes Metabolic Deficiencies in Fission Yeast

Lamichhane

Blewett

Crawford

et al. 2013

Molecular and Cellular Biology

120

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d tRNA isopentenyltransferases (Tit1) modify tRNA position 37, adjacent to the anticodon, to N 6 -isopentenyladenosine (i6A37) in all cells, yet the tRNA subsets selected for modification vary among species, and their relevance to phenotypes is unknown. We examined the function of i6A37 in Schizosaccharomyces pombe tit1؉ and tit1-⌬ cells by using a ␤-galactosidase codon-swap reporter whose catalytic activity is sensitive to accurate decoding of codon 503. i6A37 increased the activity of tRNA Cys at a cognate codon and that of tRNA Tyr at a near-cognate codon, suggesting that i6A37 promotes decoding activity generally and increases fidelity at cognate codons while decreasing fidelity at noncognate codons. S. pombe cells lacking tit1 ؉ exhibit slow growth in glycerol or rapamycin. While existing data link wobble base U34 modifications to translation of functionally related mRNAs, whether this might extend to the anticodon-adjacent position 37 was unknown. Indeed, we found a biased presence of i6A37-cognate codons in high-abundance mRNAs for ribosome subunits and energy metabolism, congruent with the observed phenotypes and the idea that i6A37 promotes translational efficiency. Polysome profiles confirmed the decreased translational efficiency of mRNAs in tit1-⌬ cells. Because subsets of i6A37-tRNAs differ among species, as do their cognate codon-sensitive mRNAs, these genomic variables may underlie associated phenotypic differences.

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mentioning

confidence: 86%

Lack of tRNA Modification Isopentenyl-A37 Alters mRNA Decoding and Causes Metabolic Deficiencies in Fission Yeast

Lamichhane

Blewett

Crawford

et al. 2013

Molecular and Cellular Biology

120

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“…In the presence of an efficient ochre suppressor, such as SUP4-o, readthrough of the ade2-1 mutation leads to a cream colony color (suppression). Deletion of MAF1 produces red colonies due to a decrease in readthrough efficiency (antisuppression) and is thought to result from hypomodification of the suppressor tRNA (10,11). As expected for a phenotype based on efficient suppressor tRNA expression and function, MAF1 alleles exhibited the same rank order with respect to defects in transcriptional repression and antisuppressor activity ( Fig.…”

Section: Effects Of Maf1 Mutations In Phenotypic Assays and In The Rementioning

confidence: 67%

Protein kinase A regulates RNA polymerase III transcription through the nuclear localization of Maf1

Moir

Lee

Haeusler

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

124

230

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Maf1 is an essential and specific mediator of transcriptional repression in the RNA polymerase (pol) III system. Maf1-dependent repression occurs in response to a wide range of conditions, suggesting that the protein itself is targeted by the major nutritional and stress-signaling pathways. We show that Maf1 is a substrate for cAMP-dependent PKA in vitro and is differentially phosphorylated on PKA sites in vivo under normal versus repressing conditions. PKA activity negatively regulates Maf1 function because strains with unregulated high PKA activity block repression of pol III transcription in vivo, and strains lacking all PKA activity are hyperrepressible. Nuclear accumulation of Maf1 is required for transcriptional repression and is regulated by two nuclear localization sequences in the protein. An analysis of PKA phosphosite mutants shows that the localization of Maf1 is affected via the N-terminal nuclear localization sequence. In particular, mutations that prevent phosphorylation at PKA consensus sites promote nuclear accumulation of Maf1 without inducing repression. These results indicate that negative regulation of Maf1 by PKA is achieved by inhibiting its nuclear import and suggest that a PKA-independent activation step is required for nuclear Maf1 to function in the repression of pol III transcription. Finally, we report a previously undescribed phenotype for Maf1 in tRNA genemediated silencing of nearby RNA pol II transcription.nuclear import ͉ phosphorylation ͉ tRNA biosynthesis T he action of all three nuclear RNA polymerases (pols) in the synthesis of rRNAs, ribosomal protein mRNAs, and tRNAs is coordinately regulated to control ribosome biogenesis and cell growth in response to nutrients and many other conditions (1). In Saccharomyces cerevisiae, Maf1 has been identified as an absolute and specific effector of repression in the pol III system (2). The diversity of conditions that signal repression, combined with the essential role of Maf1 in this process, suggests that the Maf1 protein is targeted by multiple signaling pathways.Genomewide localization of the pol III transcription apparatus has shown that nutrient deprivation and entry into stationary phase causes a significant decrease in polymerase occupancy on pol III genes (3, 4). This change is Maf1-dependent and is presumably a consequence of the direct interaction of Maf1 with the polymerase (5, 6). Consistent with this view, an in vitro system that recapitulates Maf1-dependent repression identified two steps that are inhibited as follows: polymerase recruitment to existing TFIIIB-DNA complexes and de novo assembly of the initiation factor TFIIIB onto DNA (5). In the latter step, Maf1 is thought to target the activity of TFIIIB via a direct interaction with one of its subunits, Brf1 (2, 5). However, the mechanism by which Maf1 inhibits TFIIIB-DNA assembly and transcription is not yet known.Maf1 is a phylogenetically conserved and structurally novel protein that lacks homology to any motifs of known function (6). However, three conserved doma...

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“…The S. cerevisiae maf1 deletion mutant shows elevated levels of tRNAs, including tRNA His , as a result of the lack of RNA Pol III repression (Boguta et al, 1997;Pluta et al, 2001;Kwapisz et al, 2002). To test whether CsMAF1 could function as an RNA Pol III repressor, we expressed the CsMAF1 gene in the yeast maf1 mutant upon copper induction (Fig.…”

Section: Csmaf1 Inhibits Trnamentioning

confidence: 99%

“…The yeast wild-type strain BY4742 and the MAF1 deletion mutant YI3945 (Kwapisz et al, 2002) were transformed with the citrus CsMAF1 gene cloned into pYEX-4T (Clontech) and/or the Xanthomonas citri pthA4 gene cloned into pOAD. Transformants were grown on SC-Leu-Ura (SC medium lacking leucine and uracil) plates at 30°C for 4 d. Cells were incubated in PBS buffer containing 20 mg mL 21 lyticase and disrupted by ultrasonic bath for 30 min.…”

Section: Functional Complementation Of Yeast Mutants and Northern Anamentioning

confidence: 99%

Citrus MAF1, a Repressor of RNA Polymerase III, Binds the Xanthomonas citri Canker Elicitor PthA4 and Suppresses Citrus Canker Development

et al. 2013

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Transcription activator-like (TAL) effectors from Xanthomonas species pathogens act as transcription factors in plant cells; however, how TAL effectors activate host transcription is unknown. We found previously that TAL effectors of the citrus canker pathogen Xanthomonas citri, known as PthAs, bind the carboxyl-terminal domain of the sweet orange (Citrus sinensis) RNA polymerase II (Pol II) and inhibit the activity of CsCYP, a cyclophilin associated with the carboxyl-terminal domain of the citrus RNA Pol II that functions as a negative regulator of cell growth. Here, we show that PthA4 specifically interacted with the sweet orange MAF1 (CsMAF1) protein, an RNA polymerase III (Pol III) repressor that controls ribosome biogenesis and cell growth in yeast (Saccharomyces cerevisiae) and human. CsMAF1 bound the human RNA Pol III and rescued the yeast maf1 mutant by repressing tRNAHis transcription. The expression of PthA4 in the maf1 mutant slightly restored tRNA His synthesis, indicating that PthA4 counteracts CsMAF1 activity. In addition, we show that sweet orange RNA interference plants with reduced CsMAF1 levels displayed a dramatic increase in tRNA transcription and a marked phenotype of cell proliferation during canker formation. Conversely, CsMAF1 overexpression was detrimental to seedling growth, inhibited tRNA synthesis, and attenuated canker development. Furthermore, we found that PthA4 is required to elicit cankers in sweet orange leaves and that depletion of CsMAF1 in X. citri-infected tissues correlates with the development of hyperplastic lesions and the presence of PthA4. Considering that CsMAF1 and CsCYP function as canker suppressors in sweet orange, our data indicate that TAL effectors from X. citri target negative regulators of RNA Pol II and Pol III to coordinately increase the transcription of host genes involved in ribosome biogenesis and cell proliferation.

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Up-regulation of tRNA biosynthesis affects translational readthrough in maf1- Δ mutant of Saccharomyces cerevisiae

Cited by 27 publications

References 22 publications

Lack of tRNA Modification Isopentenyl-A37 Alters mRNA Decoding and Causes Metabolic Deficiencies in Fission Yeast

Lack of tRNA Modification Isopentenyl-A37 Alters mRNA Decoding and Causes Metabolic Deficiencies in Fission Yeast

Protein kinase A regulates RNA polymerase III transcription through the nuclear localization of Maf1

Citrus MAF1, a Repressor of RNA Polymerase III, Binds the Xanthomonas citri Canker Elicitor PthA4 and Suppresses Citrus Canker Development

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