12th International Symposium on Bioluminescence & Chemiluminescence

Symposium abstracts:

Phototransformation of the wild-type A. victoria Green Fluorescent Protein with UV- and visible light leads to decarboxylation of Glutamate-222

van Thor, Jasper J.¹, Gensch, Thomas², Hellingwerf, Klaas, J.^3, Johnson, Louise, N.¹.

1. Lab. for Molecular Biophysics, University of Oxford, Rex Richards Building, South Parks Road, OX1 3QU, Oxford, UK. Email: jasper@biop.ox.ac.uk
2. Institute for Biological Information Processing IBI-1, Research Centre Jülich, D-52425 Jülich, Germany
3. Lab. for Microbiology, Swammerdam Institute for Lifesciences, University of Amsterdam, Nieuwe Achtergracht 166, 1018 WV Amsterdam, The Netherlands

Wild type Green Fluorescent Protein from Aequorea victoria predominantly absorbs at 398 nm. Illumination with UV- (254 nm) or visible light (390 nm) transforms this state (GFP₃₉₈) into a state absorbing at 483 nm (GFP₄₈₃). We have shown by X-ray structural -, spectroscopic - and mass spectrometric analysis that this photoconversion of GFP is a one-photon process, which is paralleled by decarboxylation of glutamic acid 222. We propose a mechanism in which decarboxylation is due to electron transfer between the g-carboxylate of E-222 and the p-hydroxybenzylidene-imidazolidinone chromophore of GFP, followed by reverse transfer of an electron and a proton to the remaining carbon sidechain atom of E-222. Oxidative decarboxylation of a g-carboxylate represents a new type of post-translational modification that may also occur in enzymes with high-potential reaction intermediates.

This is a preprint of an article accepted for publication in Luminescence: Copyright 2001 John
Wiley & Sons, Ltd (Wiley website)