2Q57

X-ray structure of Cerulean GFP: A tryptophan-based chromophore useful for fluorescence lifetime imaging


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2 Å
  • R-Value Free: 0.262 
  • R-Value Work: 0.188 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history

Literature

X-ray structure of Cerulean GFP: a tryptophan-based chromophore useful for fluorescence lifetime imaging.

Malo, G.D.Pouwels, L.J.Wang, M.Weichsel, A.Montfort, W.R.Rizzo, M.A.Piston, D.W.Wachter, R.M.

(2007) Biochemistry 46: 9865-9873

  • DOI: 10.1021/bi602664c
  • Also Cited By: 2WSO

  • PubMed Abstract: 
  • The crystal structure of the cyan-fluorescent Cerulean green fluorescent protein (GFP), a variant of enhanced cyan fluorescent protein (ECFP), has been determined to 2.0 A. Cerulean bears an internal fluorophore composed of an indole moiety derived f ...

    The crystal structure of the cyan-fluorescent Cerulean green fluorescent protein (GFP), a variant of enhanced cyan fluorescent protein (ECFP), has been determined to 2.0 A. Cerulean bears an internal fluorophore composed of an indole moiety derived from Y66W, conjugated to the GFP-like imidazolinone ring via a methylene bridge. Cerulean undergoes highly efficient fluorescence resonance energy transfer (FRET) to yellow acceptor molecules and exhibits significantly reduced excited-state heterogeneity. This feature was rationally engineered in ECFP by substituting His148 with an aspartic acid [Rizzo et al. (2004) Nat. Biotechnol. 22, 445], rendering Cerulean useful for fluorescence lifetime imaging microscopy (FLIM). The X-ray structure is consistent with a single conformation of the chromophore and surrounding residues and may therefore provide a structural rationale for the previously described monoexponential fluorescence decay. Unexpectedly, the carboxyl group of H148D is found in a buried position, directly contacting the indole nitrogen of the chromophore via a bifurcated hydrogen bond. Compared to the similarly constructed ECFP chromophore, the indole group of Cerulean is rotated around the methylene bridge to adopt a cis-coplanar conformation with respect to the imidazolinone ring, resulting in a close edge-to-edge contact of the two ring systems. The double-humped absorbance spectrum persists in single-crystal absorbance measurements, casting doubt on the idea that ground state conformational heterogeneity forms the basis of the two overlapping transitions. At low pH, a blue shift in absorbance of 10-15 nm suggests a pH-induced structural transition that proceeds with a time constant of 47 (+/-2) min and is reversible. Possible interpretations in terms of chromophore isomerization are presented.


    Organizational Affiliation

    Department of Chemistry and Biochemistry, Arizona State University, Tempe, Arizona 85287-1604, USA.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Cerulean Green fluorescent protein
A
256Aequorea victoriaMutation(s): 9 
Gene Names: GFP
Find proteins for P42212 (Aequorea victoria)
Go to UniProtKB:  P42212
Small Molecules
Modified Residues  1 Unique
IDChainsTypeFormula2D DiagramParent
CRF
Query on CRF
A
L-PEPTIDE LINKINGC17 H18 N4 O4THR, TRP, GLY
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2 Å
  • R-Value Free: 0.262 
  • R-Value Work: 0.188 
  • Space Group: P 21 21 21
Unit Cell:
Length (Å)Angle (°)
a = 51.232α = 90.00
b = 63.339β = 90.00
c = 69.821γ = 90.00
Software Package:
Software NamePurpose
REFMACrefinement
MOLREPphasing
MOSFLMdata reduction
SCALAdata scaling
ALSdata collection

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

  • Deposited Date: 2007-05-31 
  • Released Date: 2007-11-27 
  • Deposition Author(s): Malo, G.D.

Revision History 

  • Version 1.0: 2007-11-27
    Type: Initial release
  • Version 1.1: 2011-07-13
    Type: Version format compliance
  • Version 1.2: 2011-09-07
    Type: Non-polymer description