dorsal/arxiv
View SchemaThe adaptive filter of the yeast galactose pathway
| Authors | Serge Smidtas, Vincent Schachter, Francois Kepes |
|---|---|
| Categories | |
| ArXiv ID | q-bio/0604012 |
| URL | https://arxiv.org/abs/q-bio/0604012 |
| Journal | J. Theor. Biol. 2005 |
Abstract
In the yeast Saccharomyces cerevisiae, the interplay between galactose, Gal3p, Gal80p and Gal4p determines the transcriptional status of the genes required for galactose utilization. After an increase in galactose concentration, galactose molecules bind onto Gal3p. This event leads via Gal80p to the activation of Gal4p, which then induces GAL3 and GAL80 gene transcription. Here we propose a qualitative dynamic model, whereby these molecular interaction events represent the first two stages of a functional feedback loop that closes with the capture of activated Gal4p by newly synthesized Gal3p and Gal80p, decreasing transcriptional activation and creating again the protein complex that can bind incoming galactose molecules. Based on the differential time scales of faster protein interactions versus slower biosynthetic steps, this feedback loop functions as a derivative filter where galactose is the input step signal, and released Gal4p is the output derivative signal. One advantage of such a derivative filter is that GAL genes are expressed in proportion to the cellular requirement. Furthermore, this filter adaptively protects the cellular receptors from saturation by galactose, allowing cells to remain sensitive to variations in galactose concentrations rather than to absolute concentrations. Finally, this feedback loop, by allowing phosphorylation of some active Gal4p, may be essential to initiate the subsequent long-term response.
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"abstract": "In the yeast Saccharomyces cerevisiae, the interplay between galactose,\nGal3p, Gal80p and Gal4p determines the transcriptional status of the genes\nrequired for galactose utilization. After an increase in galactose\nconcentration, galactose molecules bind onto Gal3p. This event leads via Gal80p\nto the activation of Gal4p, which then induces GAL3 and GAL80 gene\ntranscription. Here we propose a qualitative dynamic model, whereby these\nmolecular interaction events represent the first two stages of a functional\nfeedback loop that closes with the capture of activated Gal4p by newly\nsynthesized Gal3p and Gal80p, decreasing transcriptional activation and\ncreating again the protein complex that can bind incoming galactose molecules.\nBased on the differential time scales of faster protein interactions versus\nslower biosynthetic steps, this feedback loop functions as a derivative filter\nwhere galactose is the input step signal, and released Gal4p is the output\nderivative signal. One advantage of such a derivative filter is that GAL genes\nare expressed in proportion to the cellular requirement. Furthermore, this\nfilter adaptively protects the cellular receptors from saturation by galactose,\nallowing cells to remain sensitive to variations in galactose concentrations\nrather than to absolute concentrations. Finally, this feedback loop, by\nallowing phosphorylation of some active Gal4p, may be essential to initiate the\nsubsequent long-term response.",
"arxiv_id": "q-bio/0604012",
"authors": [
"Serge Smidtas",
"Vincent Schachter",
"Francois Kepes"
],
"categories": [
"q-bio.MN",
"q-bio.CB"
],
"journal_ref": "J. Theor. Biol. 2005",
"title": "The adaptive filter of the yeast galactose pathway",
"url": "https://arxiv.org/abs/q-bio/0604012"
},
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