Affiliation:
1. Department of Chemical and Biological Engineering, University of Wisconsin—Madison, Madison, Wisconsin 53706
Abstract
ABSTRACT
When carbon sources are changed,
Saccharomyces cerevisiae
transcriptional patterns drastically change. To identify genes whose transcription can be used to quantitatively measure sugar concentrations, we searched genomic expression databases for a set of genes that are highly induced during the diauxic shift, and we used the promoters from these genes to drive expression of green fluorescent protein (GFP). Certain sugars, including glucose, fructose, and mannose, repress the promoter of
JEN1
, which encodes a lactate-pyruvate transporter, in a dose-dependent manner. Nonrepressing carbon sources include galactose, raffinose, ethanol, lactate, and glycerol.
JEN1
promoter activity is a linear function of glucose concentration when organisms are grown at a steady-state glucose concentration below 1 g/liter.
JEN1
promoter repression is specific to carbon source; heat or cold shock, osmotic stress, DNA damage, and nitrogen starvation do not significantly affect promoter activity. Activation of the
JEN1
promoter requires the Snf1 protein kinase, but multiple regulatory elements most likely combine to provide the linear relationship between
JEN1
promoter activity and sugar concentration. Thus, a
JEN1
promoter-reporter system appears to provide a good living cell biosensor for the concentration of certain sugars. The
JEN1
promoter also permits quantitative regulation of cellular functions not normally controlled by sugar concentrations. For example, a strain expressing
FLO1
under control of the
JEN1
promoter flocculates at a low glucose concentration.
Publisher
American Society for Microbiology
Subject
Ecology,Applied Microbiology and Biotechnology,Food Science,Biotechnology
Cited by
30 articles.
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