GFP-like protein

Shagin DA, Barsova EV, Yanushevich YG, Fradkov AF, Lukyanov KA, Labas YA, Semenova TN, Ugalde JA, Meyers A, Nunez JM, Widder EA, Lukyanov SA, Matz MV (2004) GFP-like proteins as ubiquitous metazoan superfamily Evolution of functional features and structural complexity. Mol Biol Evol 21 841-850... 

Dove SG, Hoegh-Guldberg O, Ranganathan S (2001) Major colour patterns of reef-building corals are due to a family of GFP-like proteins. Coral Reefs 19 197-204... 

The isolation of fluorescent proteins from nonbioluminescent species has led to the discovery of a super family of GFP-like proteins [1, 14]. Recently, six additional GFP-like proteins were isolated from A. victoria-related jellyfish [14-16]. Furthermore, a large number of GFP-like proteins have been isolated from Anthozoa species, ranging in fluorescence from green to orange-red, as well as nonflu-orescent purple-blue chromoproteins [17-19],... 

Hydrozoa, such as A. victoria, and Anthozoa both belong to the phylum Cnidaria. In addition, fluorescent proteins have been isolated from planktonic Copepods, which belong to the evolutionary distant phylum Arthropodia [14], This wide phylogenetic distribution of GFP-like proteins might implicate that these proteins developed early in evolution and hence that almost every animal taxon can potentially contain GFP homologs [1],... 

Wachter RM. The family of GFP-like proteins structure, function, photophysics and biosensor applications. Introduction and perspective. Photochem. Photobiol. 2006 82 339-344. 

Green Fluorescent Protein and Other GFP-like Proteins 79... 

More than 50 crystal structures of GFP, GFP mutants, and GFP analogs have been deposited in the protein databank [53], and of these two have their chromophore s oriented in a trans configuration. They are the intensely colored blue nonfluorescent pocilloporin pigment [54], which has a distinctly nonplanar trans configuration with most of the deviation from planarity occurring due to q> rotation, and a GFP-like protein from the sea anemone, Entacmaea quadricolor (eqFP611) [55]. 

Lukyanov et al. [56] have also proposed that CTI can occur in some GFP-like proteins, where it leads to a dark nonfluorescent state. They based their CTI model on some GFP-like proteins they have isolated. The majority of GFP-like proteins, such as DsRed, are fluorescent and have been isolated from corals. However, there are some nonfluorescent proteins that are in the so-called chromo state ( The chromo state indicates that the protein has a high extinction coefficient but a low quantum yield, whereas in the fluorescent state the protein is characterized by a high quantum yield. ) [56], Most interesting of these is asCP, a unique nonfluorescent GFP-like protein discovered in the sea anemone Anemonia sulcata [57]. Initially nonfluorescent, asCP can be made to fluoresce (kindled) by intense green light irradiation. After kindling the protein relaxes back to its nonfluorescent state, or it can be quenched instantly by short blue light irradiation. 

Table 5.1 Possible chromophore conformations in GFP-like proteins and their photophysical consequences.

The crystal structure of the dark state of asCp has recently been released [58], and as predicted it is in the trans conformation. However the chromophore has only one covalent link to the protein. Fragmentation of the protein has occurred -this has been shown to be an intrinsic step in the maturation of the asCP chromophore. The cleavage of the Cys62-chromophore bond (asCP numbering) may provide the chromophore freedom of movement not observed in GFP and other GFP-like proteins - by lowering the activation barriers for cis/trans conformational transitions it may be responsible for asCP kindling abilities. 

All GFP-like proteins exhibit a P-can motif, formed by 11 P-sheets, Fig.(l). Several short a-helical segments connect these strands, while one central helix contains the imidazolidinone chromophore. The chromophore is completely encapsulated in this cylinder, thus physicochemically very stable [48]. The a-helical caps at the top and bottom of the P-can support chromophore protection. The neighborhood of the fluorophore contains a number of charged residues and four water molecules to establish hydrogen bonds [49]. 

Unlike the other GFP-like proteins mature DsRED and its isoform shows only little pH-dependence displaying maximum fluorescence over a very broad range of pH values ranging from about 5 to 10, Fig. (19). The same holds true for equaRFPl (eqFP611) [35]. The pH-dependence of the other RFPs remains to be determined. 

Proteins of the GFP family. GFP-like proteins show a p-barrel structure that surrounds a light-active chromophore produced by the... 

GFP-like proteins, KillerRed is a dimeric FP derived from chromoprotein anm2CP. Its photosensitizing ability has been extensively studied in eell cultures and other biological systems and confirmed to be related to ROS produetion. The main ROS produced is however not but the superoxide radieal anion (02 ) and hydrogen peroxide (H2O2), formed via Type I (eleetron transfer mediated) processes. Both theoretieal and experimental structural studies have been condueted in attempts to rationalise and improve the photosensitisation ability of KillerRed, however with limited success so far. ... 

Until recently, the green fluorescent protein (avGFP) from the jellyfish Aequorea victoria was the only fluorescent protein to be widely mutated and altered for biological apphcations. Meanwhile, a family of GFP-like proteins from different organisms has emerged that share the common fl-barrel fold structure and intrinsic chromophores but represent a vast spectral range, with (E)GFP and DsRed being the most prominent representatives [33]. 

GFP from the jellyfish Aequorea victoria and its artificial mutants are widely used in cell biology and biomedical research as genetically encoded fluorescent markers. In the past decade, a number of GFP-like proteins have been found in diverse marine creatures—corals, copepods and even lower chordates. Detailed biochemical and crystallographic studies have shown a great diversity of chromo-phore structures that ejqjlain the wide spectral variations in GFP-like proteins ". ... 

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