A protein required for RNA processing and splicing in Neurospora mitochondria is related to gene products involved in cell cycle protein phosphatase functions.
The Neurospora crassa cyt-4 mutants have pleiotropic defects in mitochondrial RNA splicing, 5' and 3' end processing, and RNA turnover. Here, we show that the cyt-4+ gene encodes a 120-kDa protein with significant similarity to the SSD1/SRK1 protein of Saccharomyces cerevisiae and the DIS3 protein of Schizosaccharomyces pombe, which have been implicated in protein phosphatase functions that regulate cell cycle and mitotic chromosome segregation. The CYT-4 protein is present in mitochondria and is truncated or deficient in two cyt-4 mutants. Assuming that the CYT-4 protein functions in a manner similar to the SSD1/SRK1 and DIS3 proteins, we infer that the mitochondrial RNA splicing and processing reactions defective in the cyt-4 mutants are regulated by protein phosphorylation and that the defects in the cyt-4 mutants result from failure to normally regulate this process. Our results provide evidence that RNA splicing and processing reactions may be regulated by protein phosphorylation.
Turcq
B
B
Department of Molecular Genetics, Ohio State University, Columbus 43210.
Dobinson
K F
KF
Serizawa
N
N
Lambowitz
A M
AM
D000595:Amino Acid Sequence; D001483:Base Sequence; D002453:Cell Cycle; D003001:Cloning, Molecular; D004271:DNA, Fungal / Q000235:genetics; D004272:DNA, Mitochondrial / Q000235:genetics*; D005656:Fungal Proteins / Q000235:genetics*; D005800:Genes, Fungal; D024101:Mitochondrial Proteins; D008969:Molecular Sequence Data; D009492:Neurospora crassa / Q000235:genetics*; D010749:Phosphoprotein Phosphatases / Q000502:physiology; D012323:RNA Processing, Post-Transcriptional; D012331:RNA, Fungal / Q000235:genetics* / Q000378:metabolism; D015183:Restriction Mapping; D016415:Sequence Alignment
D004271:DNA, Fungal; D004272:DNA, Mitochondrial; D005656:Fungal Proteins; D024101:Mitochondrial Proteins; D012331:RNA, Fungal; C073287:CYT-4 protein, Neurospora crassa; D010749:Phosphoprotein Phosphatases