Gene/Protein Disease Symptom Drug Enzyme Compound
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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 SNF1 protein kinase and the associated SNF4 protein are required for release of glucose repression in Saccharomyces cerevisiae. To identify functionally related proteins, we selected genes that in multicopy suppress the raffinose growth defect of snf4 mutants. Among the nine genes recovered were two genes from the cAMP-dependent protein kinase (cAPK) pathway, MSI1 and PDE2. Increased dosage of these genes partially compensates for defects in nutrient utilization and sporulation in snf1 and snf4 null mutants, but does not restore invertase expression. These results suggest that SNF1 and cAPK affect some of the same cellular responses to nutrients. To examine the role of the cAPK pathway in regulation of invertase, we assayed mutants in which the cAPK is not modulated by cAMP. Expression of invertase was regulated in response to glucose and was dependent on SNF1 function. Thus, a cAMP-responsive cAPK is dispensable for regulation of invertase.
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PMID:Relationship of the cAMP-dependent protein kinase pathway to the SNF1 protein kinase and invertase expression in Saccharomyces cerevisiae. 131 88

We have cloned a yeast gene, SKO1, which in high copy number suppresses lethal overexpression of cAMP-dependent protein kinase. SKO1 encodes a bZIP protein that binds to the CRE motif, TGACGTCA. We found that SKO1 also binds to a CRE-like site in SUC2, a yeast gene encoding invertase which is under positive control by cAMP. A disruption of the SKO1 gene causes a partial derepression of SUC2, indicating that SKO1 is a negative regulator of the SUC2 gene. SKO1 interacts positively with MIG1, a zinc finger protein that mediates glucose repression of SUC2. A kinetic analysis revealed a complex regulation of the SUC2 mRNA in response to glucose. First, MIG1 mediates a rapid and strong repression of SUC2, which is complete within 10 minutes. Second, a MIG1-independent process causes a further slow reduction in the mRNA. Third, in the absence of MIG1, there is also a rapid but transient glucose induction of the SUC2 mRNA. This induction is correlated with a transient loss of SKO1-dependent repression.
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PMID:Yeast SKO1 gene encodes a bZIP protein that binds to the CRE motif and acts as a repressor of transcription. 143 46

Synchronous cultures of Saccharomyces cerevisiae prepared by selection of small unbudded cells from an elutriating rotor were used to measure trehalase activity during the cell cycle. After the small cells had been removed from the rotor, the remainder was used to prepare asynchronous control cultures. Both synchronous and control cultures were studied for two cell cycles. In asynchronous cultures the trehalase activity of crude cell lysates rose continuously. In synchronized populations trehalase activity increased from the beginning of budding onwards. However, around the period of cell division the enzyme activity dropped rapidly but transiently by more than 5-fold. The same changes were found during the second budding cycle. Measurements of invertase and glucose-6-phosphate dehydrogenase activities in the same synchronous and asynchronous cultures revealed a continuous increase for both enzymes. Incubation of cell lysates with cAMP-dependent protein kinase before assaying for trehalase resulted in a 2-fold enhancement of enzyme activity in asynchronous control cultures. In synchronized cells this treatment also led to a significant stimulation of trehalase activity, and largely abolished the cell-cycle-dependent oscillatory pattern of enzyme activity. These results suggest that the activity of trehalase during the cell cycle is regulated, presumably at the post-translational level, by a phosphorylation-dephosphorylation mechanism.
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PMID:Regulation of trehalase activity during the cell cycle of Saccharomyces cerevisiae. 305 78

Addition of rapidly fermentable sugars to cells of the yeast Saccharomyces cerevisiae grown on nonfermentable carbon sources causes a variety of short-term and long-term regulatory effects, leading to an adaptation to fermentative metabolism. One important feature of this metabolic switch is the occurrence of extensive transcriptional repression of a large group of genes. We have investigated transcriptional regulation of the SUC2 gene encoding repressible invertase, and of HXK1, HXK2 and GLK1 encoding the three known yeast hexose kinases during transition from derepressed to repressed growth conditions. Comparing yeast strains that express various combinations of the hexose kinase genes, we have determined the importance of each of these kinases for establishing the catabolite-repressed state. We show that catabolite repression involves two distinct mechanisms. An initial rapid response is mediated through any kinase, including Glk1, which is able to phosphorylate the available sugar. In contrast, long-term repression specifically requires Hxk2 on glucose and either Hxk1 or Hxk2 on fructose. Both HXK1 and GLK1 are repressed upon addition of glucose or fructose. However, fructose repression of Hxk1 is only transient, which is in line with its preference for fructose as substrate and its requirement for long-term fructose repression. In addition, expression of HXK1 and GLK1 is regulated through cAMP-dependent protein kinase. These results indicate that sugar sensing and establishment of catabolite repression are controlled by an interregulatory network, involving all three yeast sugar kinases and the Ras-cAMP pathway.
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PMID:Differential requirement of the yeast sugar kinases for sugar sensing in establishing the catabolite-repressed state. 891 66

Varied intensities of nitrotyrosine immunoreactivity were detected by Western blots after the reaction of proteins or enzymes with peroxynitrite (PN), a strong oxidant derived from nitric oxide. Intense immunoreactivity of cAMP-dependent protein kinase, calmodulin and most histones may depend on greater access to tyrosine residues in the reaction, whereas the absence of immunoreactivity of caspase-3, ubiquitin and S-100 proteins may reflect lack of accessibility. In addition, the changes in UV/visible absorbency were observed after PN-treatment of polynucleotides, polypeptides or proteins. Brief PN-treatment of invertase increased its enzymatic activity. Furthermore, PN-treatment of rabbit IgG decreased its recognition by anti-IgG. The results suggest that PN may chemically modify polypeptides, proteins and polynucleotides and may subsequently alter their biological activity.
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PMID:Modification of proteins and polynucleotides by peroxynitrite. 1053 71