PDBsum entry 4i3c

Fluorescent protein

PDB id: 4i3c

Contents

Protein chains

139 a.a.

Ligands

BLR ×2

Waters ×856

PDB id:

4i3c

Name:

Fluorescent protein

Title:

Crystal structure of fluorescent protein unag n57q mutant

Structure:

Bilirubin-inducible fluorescent protein unag. Chain: a, b. Synonym: unagi green fluorescent protein, unag. Engineered: yes. Mutation: yes

Source:

Anguilla japonica. Japanese eel. Organism_taxid: 7937. Expressed in: escherichia coli. Expression_system_taxid: 562.

Resolution:

2.00Å R-factor: 0.154 R-free: 0.178

Authors:

A.Kumagai,R.Ando,H.Miyatake,A.Miyawaki

Key ref:

A.Kumagai et al. (2013). A bilirubin-inducible fluorescent protein from eel muscle. Cell, 153, 1602-1611. PubMed id: 23768684 DOI: 10.1016/j.cell.2013.05.038

Date:

26-Nov-12 Release date: 19-Jun-13

Protein chains

P0DM59  (UNAG_ANGJA) -  Bilirubin-inducible fluorescent protein UnaG from Anguilla japonica

Seq: 139 a.a.

Struc: 139 a.a.*

* PDB and UniProt seqs differ at 1 residue position (black cross)

DOI no: 10.1016/j.cell.2013.05.038

Cell 153:1602-1611 (2013)

PubMed id: 23768684

A bilirubin-inducible fluorescent protein from eel muscle.

A.Kumagai, R.Ando, H.Miyatake, P.Greimel, T.Kobayashi, Y.Hirabayashi, T.Shimogori, A.Miyawaki.

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.