Real-time flow cytometric quantification of GFP expression and Gfp-fluorescence generation in Saccharomyces cerevisiae

Peter De Wulf, Luca Brambilla, M. Vanoni, Danilo Porro, Lilia Alberghina

Research output: Contribution to journalArticlepeer-review


A genetic and analytical methodology was developed based on a green fluorescent mutant protein (Gfp(S65T)) that allows the real-time quantification of gene expression in Saccharomyces cerevisiae. Using the UAS(GAL1-10)/CYC1 promoter and plasmids that are maintained in different copy numbers per cell, wild-type GFP and mutant GFP(S65T) were expressed in low to high concentration. Flow cytometric analysis was then applied to directly quantify Gfp((S65T)) (both wild type and mutant protein) expression at the single-cell level, and to indirectly measure the concentrations of non-fluorescent apoGfp((S65T)) and fluorescent Gfp((S65T)), which is autocatalytically formed from the apoprotein. Kinetics of apoGfp((S65T))/Gfp((S65T)) conversion during aerobic growth showed that the time required for complete apoGfp((S65T)) conversion is limited only by the amount of apoprotein that is expressed. When GFP(S65T) was expressed in single copy, the apoprotein did not accumulate and was instantly converted into its fluorescent form. The data indicate that an instant quantification of gene expression in S. cerevisiae is achievable based on Gfp(S65T), even if the gene is transcribed from a very strong promoter. (C) 2000 Elsevier Science B.V.

Original languageEnglish
Pages (from-to)57-64
Number of pages8
JournalJournal of Microbiological Methods
Issue number1
Publication statusPublished - Sep 2000


  • Flow cytometry
  • Gene expression
  • Green fluorescent protein
  • Saccharomyces cerevisiae

ASJC Scopus subject areas

  • Biotechnology
  • Applied Microbiology and Biotechnology
  • Microbiology


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