Noncytotoxic orange and red/green derivatives of DsRed-Express2 for whole-cell labeling

BMC Biotechnol. 2009 Apr 3;9:32. doi: 10.1186/1472-6750-9-32.


Background: Whole-cell labeling is a common application of fluorescent proteins (FPs), but many red and orange FPs exhibit cytotoxicity that limits their use as whole-cell labels. Recently, a tetrameric red FP called DsRed-Express2 was engineered for enhanced solubility and was shown to be noncytotoxic in bacterial and mammalian cells. Our goal was to create derivatives of this protein with different spectral properties.

Results: Building on previous studies of DsRed mutants, we created two DsRed-Express2 derivatives: E2-Orange, an orange FP, and E2-Red/Green, a dual-color FP with both red and green emission. We show that these new FPs retain the low cytotoxicity of DsRed-Express2. In addition, we show that these new FPs are useful as second or third colors for flow cytometry and fluorescence microscopy.

Conclusion: E2-Orange and E2-Red/Green will facilitate the production of healthy, stably fluorescent cell lines and transgenic organisms for multi-color labeling studies.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Cell Survival
  • Color
  • Escherichia coli / metabolism
  • Flow Cytometry
  • Green Fluorescent Proteins / chemistry
  • HeLa Cells
  • Humans
  • Luminescent Proteins / chemistry*
  • Microscopy, Fluorescence
  • Mutagenesis, Site-Directed
  • Saccharomyces cerevisiae / metabolism
  • Staining and Labeling / methods*


  • Luminescent Proteins
  • enhanced green fluorescent protein
  • fluorescent protein 583
  • Green Fluorescent Proteins