4LJC

Structure of an X-ray-induced photobleached state of IrisFP


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.86 Å
  • R-Value Free: 0.246 
  • R-Value Work: 0.202 

wwPDB Validation 3D Report Full Report


This is version 1.1 of the entry. See complete history

Literature

Structural evidence for a two-regime photobleaching mechanism in a reversibly switchable fluorescent protein.

Duan, C.Adam, V.Byrdin, M.Ridard, J.Kieffer-Jaquinod, S.Morlot, C.Arcizet, D.Demachy, I.Bourgeois, D.

(2013) J.Am.Chem.Soc. 135: 15841-15850

  • DOI: 10.1021/ja406860e
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 
  • Photobleaching, the irreversible photodestruction of a chromophore, severely limits the use of fluorescent proteins (FPs) in optical microscopy. Yet, the mechanisms that govern photobleaching remain poorly understood. In Reversibly Switchable Fluores ...

    Photobleaching, the irreversible photodestruction of a chromophore, severely limits the use of fluorescent proteins (FPs) in optical microscopy. Yet, the mechanisms that govern photobleaching remain poorly understood. In Reversibly Switchable Fluorescent Proteins (RSFPs), a class of FPs that can be repeatedly photoswitched between nonfluorescent and fluorescent states, photobleaching limits the achievable number of switching cycles, a process known as photofatigue. We investigated the photofatigue mechanisms in the protein IrisFP using combined X-ray crystallography, optical in crystallo spectroscopy, mass spectrometry and modeling approaches. At laser-light intensities typical of conventional wide-field fluorescence microscopy, an oxygen-dependent photobleaching pathway was evidenced. Structural modifications induced by singlet-oxygen production within the chromophore pocket revealed the oxidation of two sulfur-containing residues, Met159 and Cys171, locking the chromophore in a nonfluorescent protonated state. At laser-light intensities typical of localization-based nanoscopy (>0.1 kW/cm(2)), a completely different, oxygen-independent photobleaching pathway was found to take place. The conserved Glu212 underwent decarboxylation concomitantly with an extensive rearrangement of the H-bond network around the chromophore, and an sp(2)-to-sp(3) hybridization change of the carbon atom bridging the chromophore cyclic moieties was observed. This two-regime photobleaching mechanism is likely to be a common feature in RSFPs from Anthozoan species, which typically share high structural and sequence identity with IrisFP. In addition, our results suggest that, when such FPs are used, the illumination conditions employed in localization-based super-resolution microscopy might generate less cytotoxicity than those of standard wide-field microscopy at constant absorbed light-dose. Finally, our data will facilitate the rational design of FPs displaying enhanced photoresistance.


    Organizational Affiliation

    Université Grenoble Alpes , Institut de Biologie Structurale (IBS), F-38027 Grenoble, France.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Green to red photoconvertible GPF-like protein EosFP
A, B, C, D
229Lobophyllia hemprichiiMutation(s): 2 
Find proteins for Q5S6Z9 (Lobophyllia hemprichii)
Go to UniProtKB:  Q5S6Z9
Small Molecules
Ligands 2 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
SO4
Query on SO4

Download SDF File 
Download CCD File 
A, B, C, D
SULFATE ION
O4 S
QAOWNCQODCNURD-UHFFFAOYSA-L
 Ligand Interaction
SO3
Query on SO3

Download SDF File 
Download CCD File 
C
SULFITE ION
O3 S
LSNNMFCWUKXFEE-UHFFFAOYSA-L
 Ligand Interaction
Modified Residues  1 Unique
IDChainsTypeFormula2D DiagramParent
CR8
Query on CR8
A, B, C, D
L-PEPTIDE LINKINGC17 H16 N5 O4HIS, TYR, GLY
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.86 Å
  • R-Value Free: 0.246 
  • R-Value Work: 0.202 
  • Space Group: P 21 21 21
Unit Cell:
Length (Å)Angle (°)
a = 86.102α = 90.00
b = 96.636β = 90.00
c = 139.711γ = 90.00
Software Package:
Software NamePurpose
XDSdata reduction
MOLREPphasing
PHENIXrefinement
SCALAdata scaling
MxCuBEdata collection

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2013-10-09
    Type: Initial release
  • Version 1.1: 2013-11-06
    Type: Database references