3MPN

F177R1 mutant of LeuT


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.25 Å
  • R-Value Free: 0.214 
  • R-Value Work: 0.173 
  • R-Value Observed: 0.175 

Starting Model: experimental
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Ligand Structure Quality Assessment 


This is version 1.6 of the entry. See complete history


Literature

Structural origins of nitroxide side chain dynamics on membrane protein alpha-helical sites.

Kroncke, B.M.Horanyi, P.S.Columbus, L.

(2010) Biochemistry 49: 10045-10060

  • DOI: https://doi.org/10.1021/bi101148w
  • Primary Citation of Related Structures:  
    3MPN, 3MPQ

  • PubMed Abstract: 

    Understanding the structure and dynamics of membrane proteins in their native, hydrophobic environment is important to understanding how these proteins function. EPR spectroscopy in combination with site-directed spin labeling (SDSL) can measure dynamics and structure of membrane proteins in their native lipid environment; however, until now the dynamics measured have been qualitative due to limited knowledge of the nitroxide spin label's intramolecular motion in the hydrophobic environment. Although several studies have elucidated the structural origins of EPR line shapes of water-soluble proteins, EPR spectra of nitroxide spin-labeled proteins in detergents or lipids have characteristic differences from their water-soluble counterparts, suggesting significant differences in the underlying molecular motion of the spin label between the two environments. To elucidate these differences, membrane-exposed α-helical sites of the leucine transporter, LeuT, from Aquifex aeolicus, were investigated using X-ray crystallography, mutational analysis, nitroxide side chain derivatives, and spectral simulations in order to obtain a motional model of the nitroxide. For each crystal structure, the nitroxide ring of a disulfide-linked spin label side chain (R1) is resolved and makes contacts with hydrophobic residues on the protein surface. The spin label at site I204 on LeuT makes a nontraditional hydrogen bond with the ortho-hydrogen on its nearest neighbor F208, whereas the spin label at site F177 makes multiple van der Waals contacts with a hydrophobic pocket formed with an adjacent helix. These results coupled with the spectral effect of mutating the i ± 3, 4 residues suggest that the spin label has a greater affinity for its local protein environment in the low dielectric than on a water-soluble protein surface. The simulations of the EPR spectra presented here suggest the spin label oscillates about the terminal bond nearest the ring while maintaining weak contact with the protein surface. Combined, the results provide a starting point for determining a motional model for R1 on membrane proteins, allowing quantification of nitroxide dynamics in the aliphatic environment of detergent and lipids. In addition, initial contributions to a rotamer library of R1 on membrane proteins are provided, which will assist in reliably modeling the R1 conformational space for pulsed dipolar EPR and NMR paramagnetic relaxation enhancement distance determination.


  • Organizational Affiliation

    Department of Chemistry, University of Virginia,Charlottesville, Virginia 22904, United States.


Macromolecules
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Transporter507Aquifex aeolicusMutation(s): 1 
Gene Names: snfaq_2077
Membrane Entity: Yes 
UniProt
Find proteins for O67854 (Aquifex aeolicus (strain VF5))
Explore O67854 
Go to UniProtKB:  O67854
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupO67854
Sequence Annotations
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  • Reference Sequence
Small Molecules
Ligands 5 Unique
IDChains Name / Formula / InChI Key2D Diagram3D Interactions
BOG
Query on BOG

Download Ideal Coordinates CCD File 
B [auth A]
F [auth A]
G [auth A]
H [auth A]
I [auth A]
B [auth A],
F [auth A],
G [auth A],
H [auth A],
I [auth A],
L [auth A]
octyl beta-D-glucopyranoside
C14 H28 O6
HEGSGKPQLMEBJL-RKQHYHRCSA-N
MTN
Query on MTN

Download Ideal Coordinates CCD File 
D [auth A]S-[(1-oxyl-2,2,5,5-tetramethyl-2,5-dihydro-1H-pyrrol-3-yl)methyl] methanesulfonothioate
C10 H18 N O3 S2
MXZPGYFBZHBAQM-UHFFFAOYSA-N
LEU
Query on LEU

Download Ideal Coordinates CCD File 
C [auth A]LEUCINE
C6 H13 N O2
ROHFNLRQFUQHCH-YFKPBYRVSA-N
CL
Query on CL

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E [auth A]CHLORIDE ION
Cl
VEXZGXHMUGYJMC-UHFFFAOYSA-M
NA
Query on NA

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J [auth A],
K [auth A]
SODIUM ION
Na
FKNQFGJONOIPTF-UHFFFAOYSA-N
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.25 Å
  • R-Value Free: 0.214 
  • R-Value Work: 0.173 
  • R-Value Observed: 0.175 
  • Space Group: C 1 2 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 87.261α = 90
b = 86.222β = 95.35
c = 80.636γ = 90
Software Package:
Software NamePurpose
APSdata collection
REFMACrefinement
HKL-2000data reduction
HKL-2000data scaling
REFMACphasing

Structure Validation

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Ligand Structure Quality Assessment 


Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2010-12-01
    Type: Initial release
  • Version 1.1: 2011-07-13
    Changes: Version format compliance
  • Version 1.2: 2011-07-27
    Changes: Non-polymer description
  • Version 1.3: 2013-06-19
    Changes: Database references
  • Version 1.4: 2020-07-29
    Type: Remediation
    Reason: Carbohydrate remediation
    Changes: Advisory, Data collection, Derived calculations, Structure summary
  • Version 1.5: 2021-10-06
    Changes: Database references, Structure summary
  • Version 1.6: 2023-09-06
    Changes: Data collection, Refinement description