4I3C

Crystal structure of fluorescent protein UnaG N57Q mutant

Summary for 4I3C

• Entry DOI: 10.2210/pdb4i3c/pdb
• Related: 4I3B 4I3D
• Descriptor: Bilirubin-inducible fluorescent protein UnaG, 3-[5-[(Z)-(4-ethenyl-3-methyl-5-oxidanylidene-pyrrol-2-ylidene)methyl]-2-[[5-[(Z)-(3-ethenyl-4-methyl-5-oxidanylidene-pyrrol-2-ylidene)methyl]-3-(3-hydroxy-3-oxopropyl)-4-methyl-1H-pyrrol-2-yl]methyl]-4-methyl-1H-pyrrol-3-yl]propanoic acid (3 entities in total)
• Functional Keywords: fluorescent protein, bilirubin binding protein, lipocalin, beta barrel, cytosol
• Biological source: Anguilla japonica (Japanese eel)
• Cellular location: Cytoplasm : P0DM59
• Total number of polymer chains: 2
• Total formula weight: 32404.92

Authors

Kumagai, A.,Ando, R.,Miyatake, H.,Miyawaki, A. (deposition date: 2012-11-26, release date: 2013-06-19, Last modification date: 2023-11-08)

Primary citation

Kumagai, A.,Ando, R.,Miyatake, H.,Greimel, P.,Kobayashi, T.,Hirabayashi, Y.,Shimogori, T.,Miyawaki, A.
A bilirubin-inducible fluorescent protein from eel muscle
Cell(Cambridge,Mass.), 153:1602-1611, 2013

PubMed Abstract: The fluorescent protein toolbox has revolutionized experimental biology. Despite this advance, no fluorescent proteins have been identified from vertebrates, nor has chromogenic ligand-inducible activation or clinical utility been demonstrated. Here, we report the cloning and characterization of UnaG, a fluorescent protein from Japanese eel. UnaG belongs to the fatty-acid-binding protein (FABP) family, and expression in eel is restricted to small-diameter muscle fibers. On heterologous expression in cell lines or mouse brain, UnaG produces oxygen-independent green fluorescence. Remarkably, UnaG fluorescence is triggered by an endogenous ligand, bilirubin, a membrane-permeable heme metabolite and clinical health biomarker. The holoUnaG structure at 1.2 Å revealed a biplanar coordination of bilirubin by reversible π-conjugation, and we used this high-affinity and high-specificity interaction to establish a fluorescence-based human bilirubin assay with promising clinical utility. UnaG will be the prototype for a versatile class of ligand-activated fluorescent proteins, with applications in research, medicine, and bioengineering.

PubMed: 23768684
DOI: 10.1016/j.cell.2013.05.038

Experimental method

X-RAY DIFFRACTION (2.001 Å)