Posttranscriptional regulation of the karyogamy gene by Kem1p/Xrn1p exoribonuclease and Rok1p RNA helicase of Saccharomyces cerevisiae.
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.
Kim
Jaehee
J
Department of Microbiology, School of Bioscience and Biotechnology, Chungnam National University, Daejeon 305-764, Republic of Korea. jmkim@cnu.ac.kr
Jeon
Soonmee
S
Yang
Yun-Seok
YS
Kim
Jinmi
J
D001483:Base Sequence; D001542:Benomyl / Q000494:pharmacology; D053487:DEAD-box RNA Helicases; D004271:DNA, Fungal / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D005095:Exoribonucleases / Q000235:genetics / Q000378:metabolism*; D005659:Fungicides, Industrial / Q000494:pharmacology; D005800:Genes, Fungal; D008540:Meiosis / Q000187:drug effects / Q000235:genetics; D009154:Mutation; D010641:Phenotype; D011498:Protein Precursors / Q000494:pharmacology; D020365:RNA Helicases / Q000235:genetics / Q000378:metabolism*; D012323:RNA Processing, Post-Transcriptional; D012331:RNA, Fungal / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000187:drug effects / Q000235:genetics* / Q000502:physiology*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
D004271:DNA, Fungal; D004268:DNA-Binding Proteins; D005659:Fungicides, Industrial; C100923:KAR4 protein, S cerevisiae; C048632:MF(ALPHA)1 protein, S cerevisiae; D011498:Protein Precursors; D012331:RNA, Fungal; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; D005095:Exoribonucleases; C068398:XRN1 protein, S cerevisiae; C120858:ROK1 protein, S cerevisiae; D053487:DEAD-box RNA Helicases; D020365:RNA Helicases; D001542:Benomyl