Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.2.1.26 (invertase)
 4,927 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The SUC gene family of Saccharomyces contains six structural genes for invertase (SUC1 through SUC5 and SUC7) which are located on different chromosomes. Most yeast strains do not carry all six SUC genes and instead carry natural negative (suc0) alleles at some or all SUC loci. We determined the physical structures of SUC and suc0 loci. Except for SUC2, which is an unusual member of the family, all of the SUC genes are located very close to telomeres and are flanked by homologous sequences. On the centromere-proximal side of the gene, the conserved region contains X sequences, which are sequences found adjacent to telomeres (C. S. M. Chan and B.-K. Tye, Cell 33:563-573, 1983). On the other side of the gene, the homology includes about 4 kilobases of flanking sequence and then extends into a Y' element, which is an element often found distal to the X sequence at telomeres (Chan and Tye, Cell 33:563-573, 1983). Thus, these SUC genes and flanking sequences are embedded in telomere-adjacent sequences. Chromosomes carrying suc0 alleles (except suc20) lack SUC structural genes and portions of the conserved flanking sequences. The results indicate that the dispersal of SUC genes to different chromosomes occurred by rearrangements of chromosome telomeres.
 ...
PMID:Evolution of the dispersed SUC gene family of Saccharomyces by rearrangements of chromosome telomeres. 301 85

Low levels of invertase (EC 3.2.1.26) activity were observed in most diploid strains of S. cerevisiae used in this work. There was no effect of mating type on invertase levels, and cell surface was not a limiting factor, because an increase in ploidy did not cause further decrease in specific invertase activity. Finally, some diploids showed the activity expected from the additive effects of different SUC genes, and haploid strains possessing two SUC genes expressed very variable invertase activities depending on the strain. This suggested the existence of one or more additional genes which control the levels of invertase. Genetic analysis of SUC5 strains provided evidence of the existence of a new gene, RPS5, which drastically reduced the specific invertase activity in strains possessing active SUC alleles. The recessive allele of this gene (rps5) allows expression of higher levels of invertase. We suggest that genes similar RPS5 are responsible for the low levels of invertase activity observed in diploid strains of S. cerevisiae.
 ...
PMID:Novel genetic components controlling invertase production in Saccharomyces cerevisiae. 331 77

The yeast genome contains a dispersed family of invertase structural genes (SUC1-SUC5, SUC7). Five of these genes are located very close to telomeres and are flanked by large regions of homologous sequence; recombination between telomeres could account for the dispersal of these SUC genes to different chromosomes. The SUC2 locus, in contrast, is not near a telomere and does not share large regions of flanking homology with the other loci. We examine here the relationship between SUC2 and one of the telomeric genes, SUC7. Sequence comparison revealed homology extending from about position -624 to +1791, which is close to the end of the mRNA. The 5' noncoding sequence includes two highly conserved regions: the region between -140 and +1, which contains the TATA box and presumably other promoter elements, and a second region extending from -508 to -400, which corresponds to the upstream regulatory region.
 ...
PMID:Comparison of two yeast invertase genes: conservation of the upstream regulatory region. 390 Sep 28

Production of invertase by many strains of yeast is repressed in the presence of hexoses. This phenomenon interferes with studies on the secretion of invertase and with the preparation of large quantities of the enzyme for examination of its chemical and physical characteristics. Saccharomyces strain 303-67, a diploid carrying the single gene SUC-2 for (hexose repressible) invertase production, was subjected to ultraviolet irradiation. No single-step mutations to high level resistance were detected. By a two-step irradiation process mutants were obtained with differing degrees of resistance. The biochemical and genetic characteristics of these mutants are summarized with particular emphasis on FH4C (the most resistant). Although the steady state level of cyclic 3', 5'-adenosine monophosphate (cyclic AMP) was usually slightly higher in cells grown in low- rather than in high-glucose media, the level of cyclic AMP was not correlated with the sensitivity of invertase synthesis to glucose repression. In mutant FH4C, 1 to 2% of the total cell protein is present as invertase; synthesis of alpha-glucosidase is also resistant to repression by hexoses. This mutant does not sporulate and is probably a haploid of a-mating type with low frequency of conjugation and poor viability of conjugants. Mutants 1016 and 1710 are substantially resistant to hexose repression and still sporulate well. They may be useful for genetic analysis of hexose resistance.
 ...
PMID:Saccharomyces mutants with invertase formation resistant to repression by hexoses. 434 29

The SUC gene family of yeast (Saccharomyces) includes six structural genes for invertase (SUC1 through SUC5 and SUC7) found at unlinked chromosomal loci. A given yeast strain does not usually carry SUC+ alleles at all six loci; the natural negative alleles are called suc0 alleles. Cloned SUC2 DNA probes were used to investigate the physical structure of the SUC gene family in laboratory strains, commercial wine strains, and different Saccharomyces species. The active SUC+ genes are homologous. The suc0 allele at the SUC2 locus (suc2(0) in some strains is a silent gene or pseudogene. Other SUC loci carrying suc0 alleles appear to lack SUC DNA sequences. These findings imply that SUC genes have transposed to different chromosomal locations in closely related Saccharomyces strains.
 ...
PMID:Organization of the SUC gene family in Saccharomyces. 684 48

Utilization of sucrose as a source of carbon and energy in yeast (Saccharomyces) is controlled by the classical SUC genes, which confer the ability to produce the sucrose-degrading enzyme invertase (Mortimer and Hawthorne 1969). Mutants of S. cerevisiae strain S288C (SUC2+) unable to grow anaerobically on sucrose, but still able to use glucose, were isolated. Two major complementation groups were identified: twenty-four recessive mutations at the SUC2 locus (suc2-); and five recessive mutations defining a new locus, SNF1 (for sucrose nonfermenting), essential for sucrose utilization. Two minor complementation groups, each comprising a single member with a leaky sucrose-nonfermenting phenotype, were also identified. The Suc2 mutations isolated include four suppressible amber mutations and five mutations apparently exhibiting intragenic complementation; complementation analysis and mitotic mapping studies indicated that all of the suc2 mutations are alleles of a single gene. These results suggest that SUC2 encodes a protein, probably a dimer or multimer. No invertase activity was detected in suc2 probably a dimer or multimer. No invertase activity was detected in suc2 mutants,--The SNF1 locus is not tightly linked to SUC2. The snf1 mutations were found to be pleiotropic, preventing sucrose utilization by SUC2+ and SUC7+ strains, and also preventing utilization of galactose, maltose and several nonfermentable carbon sources. Although snf1 mutants thus display a petite phenotype, classic petite mutations do not interfere with utilization of sucrose, galactose or maltose. A common feature of all the carbon utilization systems affected by SNF1 is that all are regulated by glucose repression. The snf1 mutants were found to produce the constitutive nonglycosylated form of invertase, but failed to produce the glucose-repressible, glycosylated, secreted invertase. This failure cannot be attributed to a general defect in production of glycosylated and secreted proteins because synthesis of acid phosphatase, a glycosylated secreted protein not subject to glucose repression, was not affected by snf1 mutations. These findings suggest that the SNF1 locus is involved in the regulation of gene expression by glucose repression.
 ...
PMID:Mutants of yeast defective in sucrose utilization. 704 Jan 63

The SUC genes (SUC1-SUC7) of Saccharomyces are a family of genes that are dispersed in the yeast genome. A SUC+ allele at any locus confers the ability to produce the enzyme invertase and, thus, to ferment sucrose. Most yeast strains do not carry SUC+ alleles at all possible SUC loci. We have investigated the naturally occurring negative (suc0) alleles present at SUC loci with the aim of distinguishing between two possible models for the structure of suc0 alleles: (1) suc0 alleles correspond to a simple absence of SUC genetic information; (2) suc0 alleles are "silent" SUC genes that either produce a defective product or are not expressed. To facilitate these studies, sucrose-nonfermenting strains were constructed that are congenic to S. cerevisiae strain S288C (SUC2+), but carry at the SUC2 locus the naturally occurring negative allele, suc2(0), of strain FL100 (Lacroute 1968). These strains were used to study the genetic properties of the suc2(0) allele of FL100 and the suc0 alleles (suc1(0), suc3(0), etc.) of S288C. The suc2(0) allele was shown to revert to an active Suc+ state and to provide functional information at three points in the SUC2 gene in recombination experiments; this suc2(0) gene thus appears to be a "silent" gene. Similar tests for silent SUC genes in S288C (corresponding to loci other than SUC2) failed to reveal any additional silent genes.
 ...
PMID:Genetic evidence for a silent SUC gene in yeast. 704 Jan 64

The expression of Saccharomyces cerevisiae SUC genes is exclusively regulated by catabolic repression, mediated by glucose. Genes involved in this process have been defined by means of mutants either unable to express invertase or with constitutive phenotype, although none of the genes is specific for invertase regulation. The affected genes in mutants unable to produce invertase are designated SNFX. These genes can be assorted into two groups considering either their function in regulation of gene expression or their epistatic relationships. Mutants with constitutive phenotype have been selected either by resistance to 2-deoxyglucose or by suppression of snf mutations. Among the different genes previously outlined, some of which code for transcription factors, only the MIG1 product, a "zinc finger" protein, shows a clear capacity of binding DNA in vitro. Besides the ON/OFF switch mechanism of the expression of SUC genes, some genes seem to play a role in modulating invertase expression, either hindering or stimulating transcription. A model to define the relationship between the different gene products involved in the regulation of transcription of the SUC genes is proposed.
 ...
PMID:Genes involved in the regulation of invertase production in Saccharomyces cerevisiae. 777 93

Non-coding nucleotide sequences located 5' upstream of the transcriptional start site play an essential role in gene expression as they contain binding sites for transcription and regulatory factors. The yeast SUC gene family is a useful model to study the influence that nucleotide exchanges within the promoter regions have on their expression, since (i) these genes, regulated by glucose repression, are differentially transcribed (invertase activity produced by distinct SUC genes may show variations of about 10-fold); and (ii) promoter sequences of SUC3, SUC4, SUC5 and SUC7 are more than 99% homologous, showing only six base exchanges among all of them. Comparison of these nucleotide exchanges with the expression of each SUC gene (located either on chromosomes or on multicopy and centromeric plasmids) points out that naturally occurring base exchanges as few as one nucleotide modification (G to A transition at position -497 relative to the translational start site, C to T transition at position -460 and insertion/deletion of a T at positions -590, -586 and -435) may have a strong effect on gene expression.
 ...
PMID:Differential expression of SUC genes: a question of bases. 794 63

The comparative chromosomal locations of polymeric beta-fructosidase SUC genes have been determined by Southern blot hybridization with the SUC2 probe in 91 different strains of Saccharomyces cerevisiae. Most of the strains exhibited a single SUC2 gene, but in some strains two or three SUC genes were found. All Suc- strains carried a silent suc2(zero) sequence. The accumulation of SUC genes was observed in populations derived from sources containing sucrose and seems to be absent in strains from sources promoting the MEL gene.
 ...
PMID:Polymeric SUC genes in natural populations of Saccharomyces cerevisiae. 859 74


<< Previous 1 2 3 Next >>