6GRM

Structure of GFPmut2 crystallized at pH 6 and transferred to pH 9


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.30 Å
  • R-Value Free: 0.275 
  • R-Value Work: 0.226 
  • R-Value Observed: 0.228 

wwPDB Validation   3D Report Full Report


This is version 1.1 of the entry. See complete history


Literature

Insight into GFPmut2 pH Dependence by Single Crystal Microspectrophotometry and X-ray Crystallography.

Lolli, G.Raboni, S.Pasqualetto, E.Benoni, R.Campanini, B.Ronda, L.Mozzarelli, A.Bettati, S.Battistutta, R.

(2018) J Phys Chem B 122: 11326-11337

  • DOI: 10.1021/acs.jpcb.8b07260
  • Primary Citation of Related Structures:  
    6GO9, 6GO8, 6GQH, 6GQG, 6GRM

  • PubMed Abstract: 
  • The fluorescence of Green Fluorescent Protein (wtGFP) and variants has been exploited in distinct applications in cellular and analytical biology. GFPs emission depends on the population of the protonated (A-state) and deprotonated (B-state) forms of ...

    The fluorescence of Green Fluorescent Protein (wtGFP) and variants has been exploited in distinct applications in cellular and analytical biology. GFPs emission depends on the population of the protonated (A-state) and deprotonated (B-state) forms of the chromophore. Whereas wtGFP is pH-independent, mutants in which Ser65 is replaced by either threonine or alanine (as in GFPmut2) are pH-dependent, with a p K a around 6. Given the wtGFP pH-independence, only the structure of the protonated form was determined. The deprotonated form was deduced on the basis of the crystal structure of the Ser65Thr mutant at basic pH, assuming that it corresponds to the conformation populated in solution. Here, we present an investigation where structures of the protonated and deprotonated forms of GFPmut2 were determined from crystals grown in either MPD at pH 6 or PEG at pH 8.5, and moved to either higher or lower pH. Both crystal forms of GFPmut2 were titrated monitoring the process via polarized absorption microspectrophotometry in order to precisely correlate the protonation process with the structures. We found that (i) in solution, chromophore titration is not thermodynamically coupled with any residue and Glu222 is always protonated independent of the protonation state of the chromophore; (ii) the lack of coupling is reflected in the structural behavior of the chromophore and Glu222 environments, with only the former showing variations with pH; (iii) titrations of low-pH and high-pH grown crystals exhibit a Hill coefficient of about 0.75, indicating an anticooperative behavior not observed in solution; (iv) structures where pH was changed in the crystal point to Glu222 as the ionizable group responsible for the outset of the anticooperative behavior; and (v) in GFPmut2 the canonical GFP proton wire involving the chromophore is not interrupted at the level of Ser205 and Glu222 at basic pH as in the Ser65Thr mutant. This allows proposing the structure of the deprotonated state of GFPmut2 as an alternative model for the analogous state of wtGFP.


    Organizational Affiliation

    Dipartimento di Scienze Chimiche , Università degli Studi di Padova and Istituto di Chimica Biomolecolare, Consiglio Nazionale delle Ricerche , 35131 Padua , Italy.



Macromolecules
Find similar proteins by:  (by identity cutoff)  |  Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
Green fluorescent proteinA242Aequorea victoriaMutation(s): 3 
Gene Names: GFP
Find proteins for P42212 (Aequorea victoria)
Explore P42212 
Go to UniProtKB:  P42212
Protein Feature View
Expand
  • Reference Sequence
Small Molecules
Modified Residues  1 Unique
IDChainsTypeFormula2D DiagramParent
PIA
Query on PIA
AL-PEPTIDE LINKINGC14 H15 N3 O4ALA, TYR, GLY
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.30 Å
  • R-Value Free: 0.275 
  • R-Value Work: 0.226 
  • R-Value Observed: 0.228 
  • Space Group: P 21 21 21
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 31.323α = 90
b = 59.686β = 90
c = 108.407γ = 90
Software Package:
Software NamePurpose
PHENIXrefinement
XDSdata reduction
Aimlessdata scaling
PHASERphasing
PDB_EXTRACTdata extraction

Structure Validation

View Full Validation Report



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2018-12-19
    Type: Initial release
  • Version 1.1: 2019-04-24
    Changes: Data collection, Database references