It is well known that yeast, the humble ingredient that goes into our breads and beers, prefer to eat some sugars more than others. Glucose, their favorite food, provides more energy than any other sugar, and yeast has evolved a complex genetic network to ensure that they consume as much glucose as possible whenever it is available. UC San Diego bioengineers have recently identified a previously unknown mechanism that allows yeast to shut down the metabolism of another sugar, galactose, when they sense glucose in the environment.
The findings will be published online by the journal Nature on 30 July 2008. Narrated video of yeast growing in the experimental conditions is available at: http://video-jsoe.ucsd.edu/asx/Hasty_Nature_Yeast_7_2008.wmv.asx (Internet Explorer on a PC works best)
This research marks the first discovery of post-transcriptional gene regulation in a key model for gene regulation in higher organisms: the galactose genetic system in the yeast Saccharomyces cerevisiae.
Molecular biologists have long thought that the primary mechanism for regulating genes is through proteins called transcription factors, which can either increase or decrease the activity of a gene by binding directly to the DNA. However, a paradigm shift has occurred in recent years as researchers have shown that the control of genes frequently occurs at the intermediated stages between transcription and the formation of functional proteins. This "post-transcriptional" regulation provides cells with an additional level of control over phenotypic expression.
The UCSD team demonstrated that the glucose network actively shuts down the galactose network by degrading messenger RNA that would otherwise go on to form the enzymes needed to metabolize galactose.
"To find something new in the well-known galactose network after predicting it is extr
|Contact: Daniel Kane|
University of California - San Diego