Abstract
The major biochemical activities ascribed to Kem1p/Xrn1p of Saccharomyces cerevisiae are 5'-3' exoribonuclease functioning in RNA turnover and a microtubule-binding protein. Mutational analysis has shown that Kem1p/Xrn1p participates in microtubule-related functions such as nuclear fusion (karyogamy) during mating, chromosome transmission, and spindle pole body duplication. Here, evidence is presented that Kem1p plays a specific role in nuclear fusion by affecting, at the posttranscriptional level, the pheromone induction of the karyogamy-specific transcription factor Kar4p and the expression of Rok1p, a putative RNA helicase. We found that Rok1p itself also affects the pheromone induction of Kar4p and thereby participates in nuclear fusion. Analysis of the active-site mutations, xrn1-D206A or D208A, shows that nuclear fusion as well as the Rok1p synthesis do not require the exoribonuclease activity of Kem1p. Our data provide an important insight into the gene-specific regulatory function mediated by the general RNA-modulating enzymes.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Base Sequence
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Benomyl / pharmacology
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DEAD-box RNA Helicases
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DNA, Fungal / genetics
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DNA-Binding Proteins / genetics
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DNA-Binding Proteins / metabolism
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Exoribonucleases / genetics
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Exoribonucleases / metabolism*
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Fungicides, Industrial / pharmacology
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Genes, Fungal*
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Meiosis / drug effects
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Meiosis / genetics
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Mutation
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Phenotype
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Protein Precursors / pharmacology
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RNA Helicases / genetics
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RNA Helicases / metabolism*
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RNA Processing, Post-Transcriptional
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RNA, Fungal / genetics
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RNA, Fungal / metabolism
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Recombinant Fusion Proteins / genetics
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Recombinant Fusion Proteins / metabolism
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Saccharomyces cerevisiae / drug effects
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Saccharomyces cerevisiae / genetics*
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Saccharomyces cerevisiae / physiology*
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Saccharomyces cerevisiae Proteins / genetics
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Saccharomyces cerevisiae Proteins / metabolism*
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Saccharomyces cerevisiae Proteins / pharmacology
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Transcription Factors / genetics
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Transcription Factors / metabolism
Substances
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DNA, Fungal
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DNA-Binding Proteins
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Fungicides, Industrial
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KAR4 protein, S cerevisiae
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MF(ALPHA)1 protein, S cerevisiae
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Protein Precursors
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RNA, Fungal
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Recombinant Fusion Proteins
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Saccharomyces cerevisiae Proteins
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Transcription Factors
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Exoribonucleases
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XRN1 protein, S cerevisiae
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ROK1 protein, S cerevisiae
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DEAD-box RNA Helicases
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RNA Helicases
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Benomyl