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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Pseudouridine (Psi) residues were localized in the Saccharomyces cerevisiae spliceosomal U small nuclear RNAs (UsnRNAs) by using the chemical mapping method. In contrast to vertebrate UsnRNAs, S. cerevisiae UsnRNAs contain only a few Psi residues, which are located in segments involved in intermolecular RNA-RNA or RNA-protein interactions. At these positions, UsnRNAs are universally modified. When yeast mutants disrupted for one of the several pseudouridine synthase genes (PUS1, PUS2, PUS3, and PUS4) or depleted in rRNA-pseudouridine synthase Cbf5p were tested for UsnRNA Psi content, only the loss of the Pus1p activity was found to affect Psi formation in spliceosomal UsnRNAs. Indeed, Psi44 formation in U2 snRNA was abolished. By using purified Pus1p enzyme and in vitro-produced U2 snRNA, Pus1p is shown here to catalyze Psi44 formation in the S. cerevisiae U2 snRNA. Thus, Pus1p is the first UsnRNA pseudouridine synthase characterized so far which exhibits a dual substrate specificity, acting on both tRNAs and U2 snRNA. As depletion of rRNA-pseudouridine synthase Cbf5p had no effect on UsnRNA Psi content, formation of Psi residues in S. cerevisiae UsnRNAs is not dependent on the Cbf5p-snoRNA guided mechanism.
Mol Cell Biol 1999 Mar
PMID:Pseudouridine mapping in the Saccharomyces cerevisiae spliceosomal U small nuclear RNAs (snRNAs) reveals that pseudouridine synthase pus1p exhibits a dual substrate specificity for U2 snRNA and tRNA. 1002 1

Induction of GCN4 translation in amino acid-starved cells involves the inhibition of initiator tRNA(Met) binding to eukaryotic translation initiation factor 2 (eIF2) in response to eIF2 phosphorylation by protein kinase GCN2. It was shown previously that GCN4 translation could be induced independently of GCN2 by overexpressing a mutant tRNA(AAC)(Val) (tRNA(Val*)) or the RNA component of RNase MRP encoded by NME1. Here we show that overexpression of the tRNA pseudouridine 55 synthase encoded by PUS4 also leads to translational derepression of GCN4 (Gcd(-) phenotype) independently of eIF2 phosphorylation. Surprisingly, the Gcd(-) phenotype of high-copy-number PUS4 (hcPUS4) did not require PUS4 enzymatic activity, and several lines of evidence indicate that PUS4 overexpression did not diminish functional initiator tRNA(Met) levels. The presence of hcPUS4 or hcNME1 led to the accumulation of certain tRNA precursors, and their Gcd(-) phenotypes were reversed by overexpressing the RNA component of RNase P (RPR1), responsible for 5'-end processing of all tRNAs. Consistently, overexpression of a mutant pre-tRNA(Tyr) that cannot be processed by RNase P had a Gcd(-) phenotype. Interestingly, the Gcd(-) phenotype of hcPUS4 also was reversed by overexpressing LOS1, required for efficient nuclear export of tRNA, and los1Delta cells have a Gcd(-) phenotype. Overproduced PUS4 appears to impede 5'-end processing or export of certain tRNAs in the nucleus in a manner remedied by increased expression of RNase P or LOS1, respectively. The mutant tRNA(Val*) showed nuclear accumulation in otherwise wild-type cells, suggesting a defect in export to the cytoplasm. We propose that yeast contains a nuclear surveillance system that perceives defects in processing or export of tRNA and evokes a reduction in translation initiation at the step of initiator tRNA(Met) binding to the ribosome.
Mol Cell Biol 2000 Apr
PMID:Defects in tRNA processing and nuclear export induce GCN4 translation independently of phosphorylation of the alpha subunit of eukaryotic translation initiation factor 2. 1071 74

A novel human gene denominated TruB pseudouridine (psi) synthase homolog 1 (E. coli) (approved symbol, TRUB1) has been identified and characterized. Spanning approximately 40 kb on chromosome 10 and including 8 exons, TRUB1 is the first described human ortholog of bacterial TruB/psi55, a gene involved in tRNA pseudouridinilation. TRUB1 gene encodes a 349-amino acid product, with a VFAVHKPKGPTSA box in positions 71-83 corresponding to motif I of the TruB family (probably involved in conserving protein structure). The TruB domain of TRUB1 lies between W104 and I255, and contains another short motif, GGTLDS AARGVLVV, including the highly conserved D residue that characterizes motif II (involved in uridine recognition and in catalytic function of psi synthases). Northern blot analysis revealed that TRUB1 mRNA is widely expressed in various human tissues (especially heart, skeletal muscle and liver). Phylogenetic analysis of the TruB domain revealed another human gene (approved symbol TRUB2) encoding a conserved TruB domain, located on human chromosome 9. Thus, the human TruB family includes at least three members: i.e. DKC1 (previously identified), TRUB1 and TRUB2. The TRUB1 and TRUB2 products could be the hitherto unidentified human tRNA psi synthases. Although TRUB1 is not highly similar to DKC1/dyskerin (whose mutations cause X-linked dyskeratosis congenita) and putatively affects tRNA rather than rRNA modification, it is the most similar human protein to dyskerin. Study of TRUB1 (and TRUB2) should facilitate understanding of the molecular mechanisms of RNA modification and the involvement of psi synthases in human pathology, including dyskeratosis-like diseases.
Int J Mol Med 2003 Jun
PMID:The human TruB family of pseudouridine synthase genes, including the Dyskeratosis Congenita 1 gene and the novel member TRUB1. 1273 9

In Saccharomyces cerevisiae, HOT1-stimulated recombination has been implicated in maintaining homology between repeated ribosomal RNA genes. The ability of HOT1 to stimulate genetic exchange requires RNA polymerase I transcription across the recombining sequences. The trans-acting nuclear mutation hrm3-1 specifically reduces HOT1-dependent recombination and prevents cell growth at 37 degrees . The HRM3 gene is identical to DEG1. Excisive, but not gene replacement, recombination is reduced in HOT1-adjacent sequences in deg1Delta mutants. Excisive recombination within the genomic rDNA repeats is also decreased. The hypo-recombination and temperature-sensitive phenotypes of deg1Delta mutants are recessive. Deletion of DEG1 did not affect the rate of transcription from HOT1 or rDNA suggesting that while transcription is necessary it is not sufficient for HOT1 activity. Pseudouridine synthase 3 (Pus3p), the DEG1 gene product, modifies the anticodon arm of transfer RNA at positions 38 and 39 by catalyzing the conversion of uridine to pseudouridine. Cells deficient in pseudouridine synthases encoded by PUS1, PUS2 or PUS4 displayed no recombination defects, indicating that Pus3p plays a specific role in HOT1 activity. Pus3p is unique in its ability to modulate frameshifting and readthrough events during translation, and this aspect of its activity may be responsible for HOT1 recombination phenotypes observed in deg1 mutants.
Mol Genet Genomics 2005 Dec
PMID:DEG1, encoding the tRNA:pseudouridine synthase Pus3p, impacts HOT1-stimulated recombination in Saccharomyces cerevisiae. 1623 Nov 52