Abstract
1-Methyladenosine modification at position 58 of tRNA is catalyzed by a two-subunit methyltransferase composed of Trm6p and Trm61p in Saccharomyces cerevisiae. Initiator tRNA (tRNAi(Met)) lacking m1A58 (hypomethylated) is rendered unstable through the cooperative function of the poly(A) polymerases, Trf4p/Trf5p, and the nuclear exosome. We provide evidence that a catalytically active Trf4p poly(A) polymerase is required for polyadenylation of hypomethylated tRNAi(Met) in vivo. DNA sequence analysis of tRNAi(Met) cDNAs and Northern hybridizations of poly(A)+ RNA provide evidence that nascent pre-tRNAi(Met) transcripts are targeted for polyadenylation and degradation. We determined that a mutant U6 snRNA and an aberrant form of 5S rRNA are stabilized in the absence of Trf4p, supporting that Trf4p facilitated RNA surveillance is a global process that stretches beyond hypomethylated tRNAi(Met). We conclude that an array of RNA polymerase III transcripts are targeted for Trf4p/ Trf5p-dependent polyadenylation and turnover to eliminate mutant and variant forms of normally stable RNAs.
Publication types
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Research Support, N.I.H., Extramural
MeSH terms
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Base Sequence
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Catalytic Domain / genetics
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DNA, Fungal / genetics
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DNA-Directed DNA Polymerase / genetics
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DNA-Directed DNA Polymerase / metabolism*
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DNA-Directed RNA Polymerases / genetics
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DNA-Directed RNA Polymerases / metabolism
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Methylation
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Mutagenesis, Site-Directed
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RNA Precursors / chemistry
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RNA Precursors / genetics
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RNA Precursors / metabolism
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RNA Processing, Post-Transcriptional
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RNA, Fungal / chemistry
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RNA, Fungal / genetics
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RNA, Fungal / metabolism*
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RNA, Ribosomal, 5S / chemistry
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RNA, Ribosomal, 5S / genetics
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RNA, Ribosomal, 5S / metabolism*
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RNA, Small Nuclear / chemistry
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RNA, Small Nuclear / genetics
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RNA, Small Nuclear / metabolism
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RNA, Transfer / chemistry
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RNA, Transfer / genetics
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RNA, Transfer / metabolism
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RNA, Transfer, Met / chemistry
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RNA, Transfer, Met / genetics
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RNA, Transfer, Met / metabolism
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Saccharomyces cerevisiae / genetics
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Saccharomyces cerevisiae / metabolism*
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Saccharomyces cerevisiae Proteins / genetics
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Saccharomyces cerevisiae Proteins / metabolism*
Substances
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DNA, Fungal
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RNA Precursors
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RNA, Fungal
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RNA, Ribosomal, 5S
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RNA, Small Nuclear
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RNA, Transfer, Met
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Saccharomyces cerevisiae Proteins
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U6 small nuclear RNA
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pre-tRNA(Met)
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RNA, Transfer
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DNA-Directed RNA Polymerases
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Trf5 protein, S cerevisiae
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DNA-Directed DNA Polymerase
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PAP2 protein, S cerevisiae