%0 Journal Article
%T Amphioxus encodes the largest known family of green fluorescent proteins, which have diversified into distinct functional classes
%A Erin K Bomati
%A Gerard Manning
%A Dimitri D Deheyn
%J BMC Evolutionary Biology
%D 2009
%I BioMed Central
%R 10.1186/1471-2148-9-77
%X The amphioxus genome encodes 16 closely-related GFP-like proteins, all of which appear to be under purifying selection. We divide them into 6 clades based on protein sequence identity and show that representatives of each clade have significant differences in fluorescence intensity, extinction coefficients, and absorption profiles. Furthermore, GFPs from two clades exhibit antioxidant capacity. We therefore propose that amphioxus GFPs have diversified their functions into fluorescence, redox, and perhaps just light absorption in relation to pigmentation and/or photoprotection.The rapid radiation of amphioxus GFP into clades with distinct functions and spectral properties reveals functional plasticity of the GFP core. The high sequence similarities between different clades provide a model system to map sequence variation to functional changes, to better understand and engineer GFP.The discovery of green fluorescent protein (GFP) in the bioluminescent jellyfish Aequorea victoria [1] sparked the interest of marine ecologists, cell biologists, and spectroscopists alike. The subsequent cloning [2] and characterization [3,4] of GFP revealed that its energy-absorbing core, the chromophore, is self-generated via cyclization of a peptide triplet buried in the interior of a protective ¦Â-can protein fold [5,6]. Once oxidized using molecular oxygen, the chromophore shows high stability and absorbance of high-energy light (blue) that is efficiently re-emitted as fluorescence of lower-energy (green) light over a wide range of conditions. The ease of expression of GFP in a variety of hosts has enabled a myriad of fluorescence imaging applications, from quantifying transgene expression to probing enzyme activity and protein-protein interactions [7-10]. Its tremendous utility was recognized by the award of the 2008 Nobel prize in Chemistry.Since the discovery of GFP in Aequorea victoria, researchers have identified GFP-like proteins from other cnidarians with distinctive biochemical
%U http://www.biomedcentral.com/1471-2148/9/77