New insights into the Saccharomyces cerevisiae fermentation switch: dynamic transcriptional response to anaerobicity and glucose-excess.
BACKGROUND
The capacity of respiring cultures of Saccharomyces cerevisiae to immediately switch to fast alcoholic fermentation upon a transfer to anaerobic sugar-excess conditions is a key characteristic of Saccharomyces cerevisiae in many of its industrial applications. This transition was studied by exposing aerobic glucose-limited chemostat cultures grown at a low specific growth rate to two simultaneous perturbations: oxygen depletion and relief of glucose limitation.


RESULTS
The shift towards fully fermentative conditions caused a massive transcriptional reprogramming, where one third of all genes within the genome were transcribed differentially. The changes in transcript levels were mostly driven by relief from glucose-limitation. After an initial strong response to the addition of glucose, the expression profile of most transcriptionally regulated genes displayed a clear switch at 30 minutes. In this respect, a striking difference was observed between the transcript profiles of genes encoding ribosomal proteins and those encoding ribosomal biogenesis components. Not all regulated genes responded with this binary profile. A group of 87 genes showed a delayed and steady increase in expression that specifically responded to anaerobiosis.


CONCLUSIONS
Our study demonstrated that, despite the complexity of this multiple-input perturbation, the transcriptional responses could be categorized and biologically interpreted. By comparing this study with public datasets representing dynamic and steady conditions, 14 up-regulated and 11 down-regulated genes were determined to be anaerobic specific. Therefore, these can be seen as true "signature" transcripts for anaerobicity under dynamic as well as under steady state conditions.
van den Brink
Joost
J
Kluyver Centre for Genomics of Industrial Fermentation and Department of Biotechnology, Delft University of Technology, Julianalaan 67, 2628 BC Delft, The Netherlands. j.vandenbrink@tudelft.nl
Daran-Lapujade
Pascale
P
Pronk
Jack T
JT
de Winde
Johannes H
JH
D000693:Anaerobiosis; D005285:Fermentation; D020869:Gene Expression Profiling; D015966:Gene Expression Regulation, Fungal / Q000187:drug effects; D005947:Glucose / Q000378:metabolism / Q000494:pharmacology; D020411:Oligonucleotide Array Sequence Analysis; D010100:Oxygen / Q000378:metabolism / Q000494:pharmacology; D012441:Saccharomyces cerevisiae / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism*; D014158:Transcription, Genetic / Q000187:drug effects
D005947:Glucose; D010100:Oxygen