Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.2.1.23 (beta-galactosidase)
 14,648 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have independently identified and DNA sequenced the INO2 locus by its close proximity to the KIN1 locus in Saccharomyces cerevisiae. Mutant strains in which the INO2 chromosomal locus has been deleted show pleiotropic phenotypes under growth conditions of inositol/choline availability. Many ino2 delta cells show delocalized cell growth resulting in large cells having aberrant shapes. These mutant cells may display nuclear segregation or positioning defects as well as defects in bud formation. Furthermore, homozygous ino2 delta-1 diploids fail to sporulate. Previous studies have shown that INO2 mutants are defective in phospholipid synthesis due to an inability to derepress the INO1 gene, the structural gene for inositol-1-phosphate synthase. To identify and determine the function of Ino2p in yeast cells, we raised antibodies to a beta-galactosidase/Ino2 fusion protein. The INO2 open reading frame codes for a 304 amino acid protein with a calculated molecular weight of 39.7 kDa. Immunoblot analysis reveals two Ino2-specific proteins of approximately 44 and 46 kDa. The 44 kDa species is localized to the nucleus. Ino2p is believed to function as a positive transcriptional activator in phospholipid synthesis. Our results suggest that it affects additional pathways important to polarized cell growth and division perhaps by functioning as a more general transcriptional factor.
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PMID:INO2, a regulatory gene in yeast phospholipid biosynthesis, affects nuclear segregation and bud pattern formation. 801 48

An 815 bp region of the promoter of the Saccharomyces cerevisiae gene CTR/HNM1, encoding choline permease was sequenced and its regulatory function analysed by deletion studies in an in-frame promoter-lacZ construct. In addition to the TATA box, a 10 bp motif (consensus 5'-CATGTGAAAT-3') was found to be mandatory for CTR/HNM1 expression. This 'decamer' motif is located between nucleotides -262 and -271 and is identical in 9 of 10 bp with the regulatory motif found in the S. cerevisiae INO1 and CHO1 genes. Constructs with the 10 bp sequence show high constitutive expression, while elimination or alterations at three nucleotide positions, of the decamer motif in the context of an otherwise unchaged promoter leads to total loss of beta-galactosidase production. Expression of the CTR/HNM1 gene in wild-type cells is regulated by the phospholipid precursors inositol and choline; no such influence is seen in cells bearing mutations in the phospholipid regulatory genes INO2, INO4, and OPI1. There is no regulation by INO2 and OPI1 in the absence of the decamer motif. However constructs not containing this sequence (promoter intact to positions -213 or -152) are still controlled by INO4. Other substrates of the choline permease, i.e. ethanolamine, nitrogen mustard and nitrogen half mustard do not regulate expression of CTR/HNM1.
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PMID:Co-regulation with genes of phospholipid biosynthesis of the CTR/HNM1-encoded choline/nitrogen mustard permease in Saccharomyces cerevisiae. 826 42

Opi1p is a negative regulator of expression of phospholipid-synthesizing enzymes in the yeast Saccharomyces cerevisiae. In this work, we examined the phosphorylation of Opi1p by protein kinase C. Using a purified maltose-binding protein-Opi1p fusion protein as a substrate, protein kinase C activity was time- and dose-dependent, and dependent on the concentrations of Opi1p and ATP. Protein kinase C phosphorylated Opi1p on a serine residue. The Opi1p synthetic peptide GVLKQSCRQK, which contained a protein kinase C sequence motif at Ser(26), was a substrate for protein kinase C. Phosphorylation of a purified S26A mutant maltose-binding protein-Opi1p fusion protein by the kinase was reduced when compared with the wild-type protein. A major phosphopeptide present in purified wild-type Opi1p was absent from the purified S26A mutant protein. In vivo labeling experiments showed that the phosphorylation of Opi1p was physiologically relevant, and that the extent of phosphorylation of the S26A mutant protein was reduced by 50% when compared with the wild-type protein. The physiological consequence of the phosphorylation of Opi1p at Ser(26) was examined by measuring the effect of the S26A mutation on the expression of the phospholipid synthesis gene INO1. The beta-galactosidase activity driven by an INO1-CYC-lacI'Z reporter gene in opi1Delta mutant cells expressing the S26A mutant Opi1p was about 50% lower than that of cells expressing the wild-type Opi1p protein. These data supported the conclusion that phosphorylation of Opi1p at Ser(26) mediated the attenuation of the negative regulatory function of Opi1p on the expression of the INO1 gene.
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PMID:Phosphorylation of the yeast phospholipid synthesis regulatory protein Opi1p by protein kinase C. 1139 23

Myo-inositol exerts behavioral effects in animal models of psychiatric disorders and is effective in clinical trials in psychiatric patients. Interestingly, epi-inositol exerts behavioral effects similar to myo-inositol, even though epi-inositol is not a substrate for synthesis of phosphatidylinositol. We postulated that the behavioral effects of epi-inositol may be due to its effects on gene expression. Yeast INO1expression was measured in northern blots. INM1 was determined by beta-galactosidase activity in a strain containing the fusion gene INM1-lacZintegrated into the genome. Epi-inositol affects regulation of expression of the INO1 gene (encoding inositol-1-P synthase), even though it cannot support growth of an inositol auxotroph (suggesting that, as in mammalian cells, it is not incorporated into phosphatidylinositol). Like myo-inositol, although to a lesser extent, epi-inositol causes a significant reduction in INO1 expression, and reverses the lithium- or valproate-induced increase in INO1 expression. However, it does not affect regulation of INM1 (encoding inositol monophosphatase), the expression of which is up-regulated by myo-inositol. The observed regulatory effects of epi-inositol on expression of the most highly regulated gene in the inositol biosynthetic pathway may help to explain how this inositol isomer can exert behavioral effects without being incorporated into phosphatidylinositol.
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PMID:Epi-inositol regulates expression of the yeast INO1 gene encoding inositol-1-P synthase. 1184 Mar 10

The Opi1p transcription factor plays a negative regulatory role in the expression of UASINO-containing genes involved in phospholipid synthesis in the yeast Saccharomyces cerevisiae. The phosphorylation of Opi1p by protein kinase A (cAMP-dependent protein kinase) was examined in this work. Using a maltose-binding protein-Opi1p fusion protein as a substrate, protein kinase A activity was time- and dose-dependent and dependent on the concentrations of Opi1p and ATP. Protein kinase A phosphorylated Opi1p on multiple serine residues. The synthetic peptides SCRQKSQPSE and SQVRESLLNL containing the protein kinase A motif for Ser31 and Ser251, respectively, within Opi1p were substrates for protein kinase A. Phosphorylation of S31A and S251A mutant maltose-binding protein-Opi1p fusion proteins by protein kinase A was reduced when compared with the wild type protein, and phosphopeptides present in wild type Opi1p were absent from the S31A and S251A mutant proteins. In vivo labeling experiments showed that the extent of phosphorylation of the S31A and S251A mutant proteins was reduced when compared with the wild type protein. The physiological consequence of the phosphorylation of Opi1p at Ser31 and Ser251 was examined by measuring the effects of the S31A and S251A mutations on the expression of the UASINO-containing gene INO1. The beta-galactosidase activity driven by an INO1-CYC-lacZ reporter gene in opi1Delta mutant cells expressing the S31A and S251A mutant Opi1p proteins was elevated 42 and 35%, respectively, in the absence of inositol and 55 and 52%, respectively, in the presence of inositol when compared with cells expressing wild type Opi1p. These data supported the conclusion that phosphorylation of Opi1p at Ser31 and Ser251 mediated the stimulation of the negative regulatory function of Opi1p on the expression of the INO1 gene.
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PMID:Phosphorylation of the yeast phospholipid synthesis regulatory protein Opi1p by protein kinase A. 1266 81

In the yeast Saccharomyces cerevisiae, the expression of phospholipid biosynthetic genes, including the INO1 gene (encoding inositol-1-phosphate synthase), is coordinately regulated by a cis-acting transcriptional element, UAS(INO) (inositol-sensitive upstream activating sequence). For this paper we studied the effect of SCS2 disruption on INO1 expression. SCS2 encodes a type II membrane protein and its deletion leads to inositol auxotrophy at temperatures above 34 degrees C. We found that the expression of the INO1 gene was reduced in the scs2Delta strain even when the cells were cultured under derepressing conditions for INO1 expression. However, the beta-galactosidase gene fused with the INO1 promoter region was expressed normally in the scs2Delta strain. The phospholipid composition of scs2Delta cells was not dramatically changed compared with wild-type cells at 28 degrees C, but the phosphatidylinositol level was reduced in scs2Delta cells cultured at 34 degrees C. In addition, elevated phosphatidylcholine synthesis through the CDP-choline pathway was observed in the scs2Delta strain, and the disruption of genes involved in the CDP-choline pathway rescued the INO1 expression defect of the scs2Delta strain. These results indicate that Scs2p can contribute to coordinated phospholipid metabolism including INO1 expression by regulating phosphatidylcholine synthesis through the CDP-choline pathway.
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PMID:Role of the yeast VAP homolog, Scs2p, in INO1 expression and phospholipid metabolism. 1276