Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:6.3.5.5 (CPS)
 1,262 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The expression of gene CPA1, encoding the glutaminase subunit of the arginine pathway carbamoyl-phosphate synthetase, is repressed by arginine at a posttranscriptional level. The 5' region of CPA1 mRNA contains a 25 codon upstream open reading frame. The importance of this feature for the repression of CPA1 expression has been analyzed by oligonucleotide-directed mutagenesis and by sequencing of constitutive cis-dominant mutations obtained in vivo. The results show that the leader peptide, the product of the upstream open reading frame, plays an essential, negative role in the specific repression of CPA1 by arginine. A model of translational regulation of CPA1 is proposed that takes into account the cis-dominance of the mutations affecting the leader peptide.
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PMID:The leader peptide of yeast gene CPA1 is essential for the translational repression of its expression. 355 44

We examined the regulation of Neurospora crassa arg-2 and cpc-1 in response to amino acid availability.arg-2 encodes the small subunit of arginine-specific carbamoyl phosphate synthetase; it is subject to unique negative regulation by Arg and is positively regulated in response to limitation for many different amino acids through a mechanism known as cross-pathway control. cpc-1 specifies a transcriptional activator important for crosspathway control. Expression of these genes was compared with that of the cytochrome oxidase subunit V gene, cox-5. Analyses of mRNA levels, polypeptide pulse-labeling results, and the distribution of mRNA in polysomes indicated that Arg-specific negative regulation of arg-2 affected the levels of both arg-2 mRNA and arg-2 mRNA translation. Negative translational effects on arg-2 and positive translational effects on cpc-1 were apparent soon after cells were provided with exogenous Arg. In cells limited for His, increased expression of arg-2 and cpc-1, and decreased expression of cox-5, also had translational and transcriptional components. The arg-2 and cpc-1 transcripts contain upstream open reading frames (uORFs), as do their Saccharomyces cerevisiae homologs CPA1 and GCN4. We examined the regulation of arg-2-lacZ reporter genes containing or lacking the uORF start codon; the capacity for arg-2 uORF translation appeared critical for controlling gene expression.
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PMID:Translational regulation in response to changes in amino acid availability in Neurospora crassa. 756 72

The arginine-specific carbamoyl phosphate synthetase of Saccharomyces cerevisiae is a heterodimeric enzyme, with a 45-kDa CPA1 subunit binding and cleaving glutamine, and a 124-kDa CPA2 subunit accepting the ammonia moiety cleaved from glutamine, binding all of the remaining substrates and carrying out all of the other catalytic events. CPA2 is composed of two apparently duplicated amino acid sequences involved in binding the two ATP molecules needed for carbamoyl phosphate synthesis and a carboxyl-terminal domain which appears to be less tightly folded than the remainder of the protein. Using deletion mutagenesis, we have established that essentially all of the carboxyl-terminal domain of CPA2 is required for catalytic function and that even small truncations lead to significant changes in the CPA2 conformation. In addition, we have demonstrated that the C-terminal region of CPA2 can be expressed as an autonomously folded unit which is stabilized by specific interactions with the remainder of CPA2. We also made the unexpected finding that, even when ammonia is used as the substrate and there is no catalytic role for CPA1, interaction with CPA1 led to an increase in the Vmax of CPA2 in crude extracts.
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PMID:Requirement for the carboxyl-terminal domain of Saccharomyces cerevisiae carbamoyl-phosphate synthetase. 862 95

The gene encoding the small subunit of the arginine-specific carbamoyl phosphate synthetase, ARG2, of Magnaporthe grisea was characterized to examine the basic regulation of biosynthetic genes in this plant pathogen. The transcript of the ARG2 gene contains an upstream open reading frame (uORF) that is similar to uORFs found in the homologous genes of Neurospora crassa (arg-2) and Saccharomyces cerevisiae (CPA1), suggesting that the M. grisea gene is translationally regulated by a mechanism that is conserved in these fungi. Amino acid imbalance leads to elevated levels of ARG2 mRNA, indicating that in addition to translational control, ARG2 is subject to cross-pathway transcriptional control. A DNA-binding activity that has properties similar to those of the global transcriptional regulator mediating cross-pathway control in N. crassa was detected in M. grisea cell extracts. Thus, it appears that both specific regulation of ARG2 by arginine and global regulation of amino acid biosynthesis are present in M. grisea and highly conserved among M. grisea, N. crassa, and S. cerevisiae.
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PMID:Cross-Pathway and Pathway-Specific Control of Amino Acid Biosynthesis in Magnaporthe grisea 907 79

The gene encoding the small subunit of the arginine-specific carbamoyl phosphate synthetase, ARG2, of Magnaporthe grisea was characterized to examine the basic regulation of biosynthetic genes in this plant pathogen. The transcript of the ARG2 gene contains an upstream open reading frame (uORF) that is similar to uORFs found in the homologous genes of Neurospora crassa (arg-2) and Saccharomyces cerevisiae (CPA1), suggesting that the M. grisea gene is translationally regulated by a mechanism that is conserved in these fungi. Amino acid imbalance leads to elevated levels of ARG2 mRNA, indicating that in addition to translational control, ARG2 is subject to cross-pathway transcriptional control. A DNA-binding activity that has properties similar to those of the global transcriptional regulator mediating cross-pathway control in N. crassa was detected in M. grisea cell extracts. Thus, it appears that both specific regulation of ARG2 by arginine and global regulation of amino acid biosynthesis are present in M. grisea and highly conserved among M. grisea, N. crassa, and S. cerevisiae.
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PMID:Cross-pathway and pathway-specific control of amino acid biosynthesis in Magnaporthe grisea. 912 16

The Arg attenuator peptide (AAP) is an evolutionarily conserved peptide involved in Arg-specific negative translational control. It is encoded as an upstream open reading frame (uORF) in fungal mRNAs specifying the small subunit of Arg-specific carbamoyl phosphate synthetase. We examined the functions of the Saccharomyces cerevisiae CPA1 and Neurospora crassa arg-2 AAPs using translation extracts from S. cerevisiae, N. crassa, and wheat germ. Synthetic RNA containing AAP and firefly luciferase (LUC) sequences were used to program translation; analyses of LUC activity indicated that the AAPs conferred Arg-specific negative regulation in each system. The AAPs functioned either as uORFs or fused in-frame at the N terminus of LUC. Mutant AAPs lacking function in vivo did not function in vitro. Therefore, trans-acting factors conferring AAP-mediated regulation are in both fungal and plant systems. Analyses of ribosome stalling in the fungal extracts by primer extension inhibition (toeprint) assays showed that these AAPs acted similarly to stall ribosomes in the region immediately distal to the AAP coding region in response to Arg. The regulatory effect increased as the Arg concentration increased; all of the arginyl-tRNAs examined appeared maximally charged at low Arg concentrations. Therefore, AAP-mediated Arg-specific regulation appeared independent of the charging status of arginyl-tRNA.
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PMID:A highly conserved mechanism of regulated ribosome stalling mediated by fungal arginine attenuator peptides that appears independent of the charging status of arginyl-tRNAs. 1060 10

The Neurospora crassa arg-2 and the Saccharomyces cerevisiae ortholog CPA1 encode the arginine-specific carbamoyl-phosphate synthetase (CPS-A) small subunit. Arginine decreases synthesis of this subunit through the action of a 5' upstream open reading frame in the mRNA that encodes a cis-regulatory element, the arginine attenuator peptide (AAP), which stalls ribosomes in response to arginine. We performed a comparative analysis of the genomic structure and predicted peptide sequence of the AAP and CPS-A small subunit across many fungi. Differences at the genomic level included variation in intron number and position within the AAP and CPS-A coding regions and differences in known regulatory motifs. Although differences exist in AAP sequence, there were three absolutely conserved amino acid residues in the predicted peptide, including an aspartic acid crucial for arginine-dependent regulation of arg-2 and CPA1. A diverged Basidiomycete AAP was shown to retain function as an Arg-specific negative regulator of translation.
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PMID:Evolutionary changes in the fungal carbamoyl-phosphate synthetase small subunit gene and its associated upstream open reading frame. 1697 58