Accumulation of glycogen and trehalose in nutrient-limited cultures of Saccharomyces cerevisiae is negatively correlated with the specific growth rate. Additionally, glucose-excess conditions (i.e., growth limitation by nutrients other than glucose) are often implicated in high-level accumulation of these storage carbohydrates. The present study investigates how the identity of the growth-limiting nutrient affects accumulation of storage carbohydrates in cultures grown at a fixed specific growth rate. In anaerobic chemostat cultures (dilution rate, 0.10 h(-1)) of S. cerevisiae, the identity of the growth-limiting nutrient (glucose, ammonia, sulfate, phosphate, or zinc) strongly affected storage carbohydrate accumulation. The glycogen contents of the biomass from glucose- and ammonia-limited cultures were 10- to 14-fold higher than those of the biomass from cultures grown under the other three glucose-excess regimens. Trehalose levels were specifically higher under nitrogen-limited conditions. These results demonstrate that storage carbohydrate accumulation in nutrient-limited cultures of S. cerevisiae is not a generic response to excess glucose but instead is strongly dependent on the identity of the growth-limiting nutrient. While transcriptome analysis of wild-type and msn2Delta msn4Delta strains confirmed that transcriptional upregulation of glycogen and trehalose biosynthesis genes is mediated by Msn2p/Msn4p, transcriptional regulation could not quantitatively account for the drastic changes in storage carbohydrate accumulation. The results of assays of glycogen synthase and glycogen phosphorylase activities supported involvement of posttranscriptional regulation. Consistent with the high glycogen levels in ammonia-limited cultures, the ratio of glycogen synthase to glycogen phosphorylase in these cultures was up to eightfold higher than the ratio in the other glucose-excess cultures.
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http://dx.doi.org/10.1128/AEM.01464-09 | DOI Listing |
J Phycol
June 2016
Molecular and Cell Biology Department, University of Cape Town, Rondebosch, Cape Town, 7700, South Africa.
Inorganic nitrogen has been identified as the major growth-limiting nutritional factor affecting Gracilaria gracilis populations in South Africa. Although the physiological mechanisms implemented by G. gracilis for adaption to low nitrogen environments have been investigated, little is known about the molecular mechanisms of these adaptions.
View Article and Find Full Text PDFMetabolomics
June 2015
Cambridge Systems Biology Centre & Department of Biochemistry, University of Cambridge, Cambridge, CB2 1GA UK ; Department of Chemical Engineering, Bogazici University, Istanbul, Turkey.
Genome-scale stoichiometric models, constrained to optimise biomass production are often used to predict mutant phenotypes. However, for , the representation of biomass in its metabolic model has hardly changed in over a decade, despite major advances in analytical technologies. Here, we use the stoichiometric model of the yeast metabolic network to show that its ability to predict mutant phenotypes is particularly poor for genes encoding enzymes involved in energy generation.
View Article and Find Full Text PDFJ Bacteriol
September 2012
Max Planck Institute for Developmental Biology, Department of Protein Evolution, Tuebingen, Germany.
Colicin M (Cma) is a protein toxin produced by Escherichia coli that kills sensitive E. coli cells by inhibiting murein biosynthesis in the periplasm. Recombinant plasmids carrying cbrA (formerly yidS) strongly increased resistance of cells to Cma, whereas deletion of cbrA increased Cma sensitivity.
View Article and Find Full Text PDFBioinformation
April 2011
Biology department, Ecole Normale Superieure, ENS-Kouba, PB 92, Algiers, Algeria.
Unlabelled: Nitrogen is one of the major growth-limiting nutrients for plants: The main source of nitrogen in most of the higher plants is nitrate taken up through roots. Nitrate can be reduced both in the chloroplasts (photosynthetic tissues) and in proplastes (nonphotosynthetic tissues) such as roots. Ferredoxin-nitrite reductase (NiR) catalyses the reduction of nitrite to ammonium in the second step of the nitrate- assimilation pathway.
View Article and Find Full Text PDFMol Biol Cell
January 2010
Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544, USA.
Microbes tailor their growth rate to nutrient availability. Here, we measured, using liquid chromatography-mass spectrometry, >100 intracellular metabolites in steady-state cultures of Saccharomyces cerevisiae growing at five different rates and in each of five different limiting nutrients. In contrast to gene transcripts, where approximately 25% correlated with growth rate irrespective of the nature of the limiting nutrient, metabolite concentrations were highly sensitive to the limiting nutrient's identity.
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