A screen for kinases affecting the cytosolic glucose level in Saccharomyces cerevisiae using a glucose biosensor: characterization of a novel kinase involved in regulation of the glucose transport
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Møller-Hansen, Iben1, Forfatter
Engelbrecht, Jacob1, Vejleder
Frommer, Wolf B.1, Vejleder
1Det Biovidenskabelige Fakultet, København, Danmark, diskurs:18              
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 Abstract: Glucose is the preferred carbon source of the budding yeast Saccharomyces cerevisiae and used for fermentative metabolism. Glucose also functions as a hormone signalling repression or induction of a wide range of genes primarily involved in metabolism, biosynthesis of reserve carbohydrates and cell cycle control. The Ras/cAMP/PKA-, Snf1/Snf4/Gal83- and Snf3/Rgt2 pathways mediate the major cellular change in response to glucose by activating or deactivating transcription factors and other regulatory proteins. The central Ras/cAMP/PKA-, Snf1/Snf4/Gal83- and Snf3/Rgt2 pathways are well studied, but what links the pathways together and how an extracellular glucose signal is sensed, is not very well understood. Since both the Ras/cAMP/PKA-, Snf1/Snf4/Gal83- and Snf3/Rgt2 pathways include kinases as their major regulatory element, it has been hypothesized that the proteins linking the regulatory elements together also are kinases. To test this hypothesis a collection containing all known kinases in S. cerevisiae over expressed, was screened using a glucose biosensor. Strains over expressing the kinases YDL025c, YDL028c, YDL017w and Fus3 were shown to influencing the cytosolic glucose level in response to extracellular glucose, in cells grown on non-fermentative carbon sources. The uncharacterized kinase YDL025c has previously been shown to interact with both Yck1, Snf1 and Tpk1 all kinases involved in the key glucose signalling pathways. YDL025c was further shown to cause a lower cytosolic glucose level by repressing a hexose transporter, directly or indirectly. An YDL025c-GFP fusion localized to the periphery of the cell and the YDL025c-GFP fusion did not show a reduction in expression when grown in the presence of glucose. YDL025c was hypothesized to be a serine/threonine kinase with catalytic domains similar to the regulator of a general amino acid transporter Npr1. YDL025c was also hypothesized to be phosphorylated at a serine or tyrosine. Of the strains containing the over expressed kinases Yck1, Snf1 and Tpk1, the strain over expressing Yck1 showed the largest change in cytosolic glucose level in response to extracellular glucose.
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 Type: Speciale
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Sprog: English - eng
 Datoer: 2008
 Sider: 87 pages
 Publiceringsinfo: København, Danmark : Institut for Grundvidenskab og Miljø
 Indholdsfortegnelse: -
 Note: Biology - Biotechnology, Biologi - Bioteknologi
 Type: Speciale
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