A colourless green fluorescent protein homologue from the non-fluorescent hydromedusa Aequorea coerulescens and its fluorescent mutants

Biochem J. 2003 Jul 15;373(Pt 2):403-8. doi: 10.1042/BJ20021966.


We have cloned an unusual colourless green fluorescent protein (GFP)-like protein from Aequorea coerulescens (acGFPL). The A. coerulescens specimens displayed blue (not green) luminescence, and no fluorescence was detected in these medusae. Escherichia coli expressing wild-type acGFPL showed neither fluorescence nor visible coloration. Random mutagenesis generated green fluorescent mutants of acGFPL, with the strongest emitters found to contain an Glu(222)-->Gly (E222G) substitution, which removed the evolutionarily invariant Glu(222). Re-introduction of Glu(222) into the most fluorescent random mutant, named aceGFP, converted it into a colourless protein. This colourless aceGFP-G222E protein demonstrated a novel type of UV-induced photoconversion, from an immature non-fluorescent form into a green fluorescent form. Fluorescent aceGFP may be a useful biological tool, as it was able to be expressed in a number of mammalian cell lines. Furthermore, expression of a fusion protein of 'humanized' aceGFP and beta-actin produced a fluorescent pattern consistent with actin distribution in mammalian cells.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • COS Cells / cytology
  • Cell Line
  • Chlorocebus aethiops
  • Escherichia coli / genetics
  • Fibroblasts / metabolism
  • Green Fluorescent Proteins
  • Humans
  • Luminescent Proteins / chemistry
  • Luminescent Proteins / genetics*
  • Luminescent Proteins / metabolism*
  • Luminescent Proteins / radiation effects
  • Mice
  • Molecular Sequence Data
  • Mutagenesis, Site-Directed
  • Point Mutation
  • Recombinant Fusion Proteins
  • Scyphozoa / chemistry*
  • Spectrometry, Fluorescence
  • Transfection


  • Luminescent Proteins
  • Recombinant Fusion Proteins
  • Green Fluorescent Proteins

Associated data

  • GENBANK/AY151052
  • GENBANK/AY233272