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Query: EC:3.2.1.26 (invertase)
 4,927 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The SUC2 gene produces two differently regulated mRNAs that encode two forms of invertase. The 1.9-kilobase mRNA encoding secreted invertase is regulated by glucose (carbon catabolite) repression, and the 1.8-kilobase mRNA encoding intracellular invertase is synthesized constitutively. Previous work has shown that the 5' noncoding region between -650 and -418 is required for derepression of secreted invertase in response to glucose deprivation. We show here that this upstream region can confer glucose-repressible expression to a heterologous gene, a LEU2-lacZ gene fusion, that is not normally regulated by glucose repression. This expression was found to respond appropriately to mutations in trans-acting genes that affect regulation of SUC2 expression. Mutations in the SNF1 through SNF6 loci reduced derepression of beta-galactosidase, and a mutation at the SSN6 locus caused constitutive expression. These findings indicate that the SUC2 upstream region mediates the regulatory effects of these genes and suggest that regulation occurs at the level of transcription. In addition, the upstream region was partially active in the inverted orientation.
Mol Cell Biol 1985 Oct
PMID:Upstream region of the SUC2 gene confers regulated expression to a heterologous gene in Saccharomyces cerevisiae. 393 53

A new mutation has been described which confers resistance to catabolite repression in Saccharomyces cerevisiae. The mutant allele, termed grr-1 for glucose repression-resistant, is characterized by insensitivity to glucose repression for the cytoplasmic enzymes invertase, maltase, and galactokinase, as well as the mitochondrial enzyme cytochrome c oxidase. Hexokinase levels in grr-1 mutants are approximately 3-fold higher than the corresponding activity of the parental strain. Although the grr-1 allele is expressed phenotypically similarly to the hex-1 (hxk-2) and hex-2 mutations described by Entian et al. (1977) and Zimmermann and Scheel (1977) respectively, we have shown genetically and physiologically that grr-1 represents a new class of mutation.
Mol Gen Genet 1984
PMID:Isolation and characterization of a pleiotropic glucose repression resistant mutant of Saccharomyces cerevisiae. 632 21

The SUC2 gene of Saccharomyces cerevisiae encodes two differently regulated mRNAs (1.8 and 1.9 kilobases) that differ at their 5' ends. The larger RNA encodes a secreted, glycosylated form of invertase and the smaller RNA encodes an intracellular, nonglycosylated form. We have determined the nucleotide sequence of the amino-terminal coding region of the SUC2 gene and its upstream flanking region and have mapped the 5' ends of the SUC2 mRNAs relative to the DNA sequence. The 1.9-kilobase RNA contains a signal peptide coding sequence and presumably encodes a precursor to secreted invertase. The 1.8-kilobase RNA does not include the complete coding sequence for the signal peptide. The nucleotide sequence data prove that SUC2 is a structural gene for invertase, and translation of the coding information provides the complete amino acid sequence of an S. cerevisiae signal peptide.
Mol Cell Biol 1983 Mar
PMID:The secreted form of invertase in Saccharomyces cerevisiae is synthesized from mRNA encoding a signal sequence. 634 17

A functional SNF1 gene product is required to derepress expression of many glucose-repressible genes in Saccharomyces cerevisiae. Strains carrying a snf1 mutation are unable to grow on sucrose, galactose, maltose, melibiose, or nonfermentable carbon sources; utilization of these carbon sources is regulated by glucose repression. The inability of snf1 mutants to utilize sucrose results from failure to derepress expression of the structural gene for invertase at the RNA level. We isolated recombinant plasmids carrying the SNF1 gene by complementation of the snf1 defect in S. cerevisiae. A 3.5-kilobase region is common to the DNA segments cloned in five different plasmids. Transformation of S. cerevisiae with an integrating vector carrying a segment of the cloned DNA resulted in integration of the plasmid at the SNF1 locus. This result indicates that the cloned DNA is homologous to sequences at the SNF1 locus. By mapping a plasmid marker linked to SNF1 in this transformant, we showed that the SNF1 gene is located on chromosome IV. We then mapped snf1 to a position 5.6 centimorgans distal to rna3 on the right arm; snf1 is not extremely closely linked to any previously mapped mutation.
Mol Cell Biol 1984 Jan
PMID:Cloning and genetic mapping of SNF1, a gene required for expression of glucose-repressible genes in Saccharomyces cerevisiae. 636 12

The SNF1 gene of Saccharomyces cerevisiae is essential for normal regulation of gene expression by glucose repression. A functional SNF1 gene product is required to derepress many glucose-repressible genes in response to conditions of low external glucose. In the case of the SUC2 structural gene for invertase, SNF1 acts at the RNA level. We have reported the isolation of a cloned gene that complements the snf1 defect in S. cerevisiae and that is homologous to DNA at the SNF1 locus (J. L. Celenza and M. Carlson, Mol. Cell. Biol. 4:49-53, 1984). In this work we identified a 2.4-kilobase polyadenylate-containing RNA encoded by the SNF1 gene and showed that its level is neither regulated by glucose repression nor dependent on a functional SNF1 product. The position of the SNF1 RNA relative to the cloned DNA was mapped, and the direction of transcription was determined. The cloned DNA was used to disrupt the SNF1 gene at its chromosomal locus. Gene disruption resulted in A Snf1- phenotype, thereby proving that the cloned gene is the SNF1 gene and showing that the phenotype of a true null mutation is indistinguishable from that of previously isolated snf1 mutations.
Mol Cell Biol 1984 Jan
PMID:Structure and expression of the SNF1 gene of Saccharomyces cerevisiae. 636 13

A selection system has been devised for isolating hexokinase PII structural gene mutants that cause defects in carbon catabolite repression, but retain normal catalytic activity. We used diploid parental strains with homozygotic defects in the hexokinase PI structural gene and with only one functional hexokinase PII allele. Of 3,000 colonies tested, 35 mutants (hex1r) did not repress the synthesis of invertase, maltase, malate dehydrogenase, and respiratory enzymes. These mutants had additional hexokinase PII activity. In contrast to hex1 mutants (Entian et al., Mol. Gen. Genet. 156:99-105, 1977; F.K. Zimmermann and I. Scheel, Mol. Gen. Genet. 154:75-82, 1977), which were allelic to structural gene mutants of hexokinase PII and had no catalytic activity (K.-D. Entian, Mol. Gen. Gent. 178:633-637, 1980), the hex1r mutants sporulated hardly at all or formed aberrant cells. Those ascospores obtained were mostly inviable. As the few viable hex1r segregants were sterile, triploid cells were constructed to demonstrate allelism between hex1r mutants and hexokinase PII structural gene mutants. Metabolite concentrations, growth rate, and ethanol production were the same in hex1r mutants and their corresponding wild-type strains. Recombination of hexokinase and glucokinase alleles gave strains with different specific activities. The defect in carbon catabolite repression was strongly associated with the defect in hexokinase PII and was independent of the glucose phosphorylating capacity. Hence, a secondary effect caused by reduced hexose phosphorylation was not responsible for the repression defect in hex1 mutants. These results, and those with the hex1r mutants isolated, strongly supported our earlier hypothesis that hexokinase PII is a bifunctional enzyme with (i) catalytic activity and (ii) a regulatory component triggering carbon catabolite repression (Entian, Mol. Gen. Genet. 178:633-637, 1980; K.-D. Entian and D. Mecke, J. Biol. Chem. 257:870-874, 1982).
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PMID:Saccharomyces cerevisiae mutants provide evidence of hexokinase PII as a bifunctional enzyme with catalytic and regulatory domains for triggering carbon catabolite repression. 637 Sep 59

A single structural gene, SUC2, encodes both secreted and cytoplasmic invertase in Saccharomyces cerevisiae. It is known that the unprocessed polypeptides which differ by a secretion signal sequence are encoded by separate mRNAs. This unusual transcriptional organization raises the question as to the degree to which the transcripts can be independently regulated. To define a system for studying this problem, we examined invertase transcription after various physiological perturbations of cells: rapid catabolite derepression, heat shock, and cell cycle arrest. With each treatment, fluctuations in mRNA levels for both cytoplasmic and secreted invertase were observed. We concluded that (i) catabolite-derepressed synthesis of the mRNAs occurs rapidly after a drop in glucose, is a sustained response, and does not require de novo protein synthesis; (ii) heat shock transcription of both invertase mRNAs is, in contrast, a brief and transient response requiring de novo protein synthesis; and (iii) alpha-mating hormone treatment (G1 phase arrest and release) results in regular and coordinated synthesis of both mRNAs midway between rounds of histone mRNA synthesis. We propose that invertase mRNA regulation involves constitutively synthesized transcriptional factors (observed during catabolite derepression) and transient factors (observed during heat shock and possibly during synchronous growth). Moreover, the mRNA levels for secreted and cytoplasmic invertase can be independently regulated.
Mol Cell Biol 1984 Sep
PMID:Cytoplasmic and secreted Saccharomyces cerevisiae invertase mRNAs encoded by one gene can be differentially or coordinately regulated. 638 45

Various amino acid insertions have been introduced into the proximal portion of the signal sequence of secreted yeast invertase. The altered invertase genes have been reintroduced into yeast and monitored for their ability to direct synthesis of secreted invertase in vivo. The insertions should alter the signal polypeptide local secondary structure as predicted by the Chou and Fasman rules (1978). Secretion of these altered invertase polypeptides is not blocked by the amino acid insertions.
Mol Gen Genet 1984
PMID:Conformational alterations in the proximal portion of the yeast invertase signal peptide do not block secretion. 639 90

The SUC2 gene produces two mRNAs with different 5' ends that encode two forms of invertase. The 1.9-kilobase mRNA encoding secreted invertase is regulated by glucose repression (carbon catabolite repression), and the 1.8-kilobase mRNA encoding intracellular invertase is produced constitutively at low levels. To identify 5' noncoding sequences essential for regulated expression of SUC2, we constructed in vitro a series of deletions and inserted them into the yeast genome at the chromosomal SUC2 locus. Analysis of the effects of each deletion on SUC2 gene expression identified an upstream region required for derepression of secreted invertase synthesis. The 3' boundary of this region is near -418. The 5' boundary does not appear to be sharply defined, but lies ca. 100 base pairs upstream. A deletion extending from -418 to -140 allowed high-level derepression, indicating that no essential sequences lie between the upstream region and the TATA box at -133 and that the upstream region can be moved 279 base pairs closer to the transcriptional start site. Interactions between the deletions and several unlinked mutations affecting the regulation of SUC2 gene expression were examined. Sequences between -1,900 and -86 are dispensable for expression of the 1.8-kilobase mRNA.
Mol Cell Biol 1984 Dec
PMID:Upstream region required for regulated expression of the glucose-repressible SUC2 gene of Saccharomyces cerevisiae. 639 5

The yeast SUC2 gene codes for the secreted enzyme invertase. A series of 16 different-sized gene fusions have been constructed between this yeast gene and the Escherichia coli lacZ gene, which codes for the cytoplasmic enzyme beta-galactosidase. Various amounts of SUC2 NH2-terminal coding sequence have been fused in frame to a constant COOH-terminal coding segment of the lacZ gene, resulting in the synthesis of hybrid invertase-beta-galactosidase proteins in Saccharomyces cerevisiae. The hybrid proteins exhibit beta-galactosidase activity, and they are recognized specifically by antisera directed against either invertase or beta-galactosidase. Expression of beta-galactosidase activity is regulated in a manner similar to that observed for invertase activity expressed from a wild-type SUC2 gene: repressed in high-glucose medium and derepressed in low-glucose medium. Unlike wild-type invertase, however, the invertase-beta-galactosidase hybrid proteins are not secreted. Rather, they appear to remain trapped at a very early stage of secretory protein transit: insertion into the endoplasmic reticulum (ER). The hybrid proteins appear only to have undergone core glycosylation, an ER process, and do not receive the additional glycosyl modifications that take place in the Golgi complex. Even those hybrid proteins containing only a short segment of invertase sequences at the NH2 terminus are glycosylated, suggesting that no extensive folding of the invertase polypeptide is required before initiation of transmembrane transfer. beta-Galactosidase activity expressed by the SUC2-lacZ gene fusions cofractionates on Percoll density gradients with ER marker enzymes and not with other organelles. In addition, the hybrid proteins are not accessible to cell-surface labeling by 125I. Accumulation of the invertase-beta-galactosidase hybrid proteins within the ER does not appear to confer a growth-defective phenotype to yeast cells. In this location, however, the hybrid proteins and the beta-galactosidase activity they exhibit could provide a useful biochemical tag for yeast ER membranes.
Mol Cell Biol 1984 Nov
PMID:Invertase beta-galactosidase hybrid proteins fail to be transported from the endoplasmic reticulum in Saccharomyces cerevisiae. 644 5


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