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Transcriptional responses of Saccharomyces cerevisiae to preferred and nonpreferred nitrogen sources in glucose-limited chemostat cultures

Authors


  • Present address: Viktor M. Boer, Lewis-Sigler Institute for Integrative Genomics, Carl Icahn Laboratory, Princeton University, Washington Road, Princeton, NJ 08544, USA.

  • Present address: Yalun Arifin, Australian Institute for Bioengineering and Nanotechnology (AIBN), Corner College and Cooper Rds, The University of Queensland, Brisbane QLD 4072, Australia.

  • Present address: Matthew D.W. Piper, Department of Biology, University College London, Darwin Bldg., Gower St, London WC1E 6BT, UK.

  • Editor: Terrance Cooper

Correspondence: Jean-Marc Daran, Department of Biotechnology, Delft University of Technology, Julianalaan 67, 2628 BC Delft, The Netherlands. Tel.: +31 15 2782412; fax: +31 15 2782355; e-mail: j.g.daran@udelft.nl

Abstract

Aerobic, glucose-limited chemostat cultures of Saccharomyces cerevisiae grown with six different nitrogen sources were subjected to transcriptome analysis. The use of chemostats enabled an analysis of nitrogen-source-dependent transcriptional regulation at a fixed specific growth rate. A selection of preferred (ammonium and asparagine) and nonpreferred (leucine, phenylalanine, methionine and proline) nitrogen sources was investigated. For each nitrogen source, distinct sets of genes were induced or repressed relative to the other five nitrogen sources. In total, 131 such ‘signature transcripts’ were identified in this study. In addition to signature transcripts, genes were identified that showed a transcriptional coresponse to two or more of the six nitrogen sources. For example, 33 genes were transcriptionally upregulated in leucine-grown, phenylalanine-grown and methionine-grown cultures; this was partly attributed to the involvement of common enzymes in the dissimilation of these amino acids. In addition to specific transcriptional responses elicited by individual nitrogen sources, their impact on global regulatory mechanisms such as nitrogen catabolite repression (NCR) were monitored. NCR-sensitive gene expression in the chemostat cultures showed that ammonium and asparagine were ‘rich’ nitrogen sources. By this criterion, leucine, proline and methionine were ‘poor’ nitrogen sources, and phenylalanine showed an ‘intermediate’ NCR response.

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