1SX7

Use of an ion-binding site to bypass the 1000-atom limit to ab initio structure determination by direct methods

Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.06 Å
  • R-Value Free: 0.145 
  • R-Value Work: 0.120 

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This is version 1.4 of the entry. See complete history. 

Literature

Use of an ion-binding site to bypass the 1000-atom limit to structure determination by direct methods.

Mooers, B.H., Matthews, B.W.

(2004) Acta Crystallogr.,Sect.D 60: 1726-1737

  • DOI: 10.1107/S0907444904017020
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 

    • Proteins with more than 1000 non-H atoms and without heavy-atom prosthetic groups are very difficult to solve by ab initio direct methods. T4 lysozyme is being used to explore these limits. The protein has 1309 non-H atoms, seven S atoms, no disulfid ...

    Proteins with more than 1000 non-H atoms and without heavy-atom prosthetic groups are very difficult to solve by ab initio direct methods. T4 lysozyme is being used to explore these limits. The protein has 1309 non-H atoms, seven S atoms, no disulfide bonds and no heavy-atom prosthetic group. It is recalcitrant to structure determination by direct methods using X-ray diffraction data to 0.97 A. It is shown here that it is possible to obtain a truly ab initio structure determination of a variant of the protein that has an Rb+ (Z = 37) binding site. Using diffraction data to 1.06 A resolution, the direct-methods programs SIR2002 and ACORN independently solved the structure in about 20 h. The bound Rb+, which contributes about 1.7% of the total scattering, does not appear to distort the structure or to inhibit refinement (R factor 12.1%). The phases obtained via SIR2002 or ACORN are in good agreement with those from a reference structure obtained from conventional molecular-substitution and refinement procedures (average error in the figure-of-merit-weighted phases of less than 25 degrees). Thus, proteins with more than 1000 atoms that include halide-binding or other such sites may be amenable to structure determination by ab initio direct methods. The direct-methods approaches are also compared with structure determination via use of the anomalous scattering of the Rb+ ion. As shown by examples, high-resolution structures determined by direct methods can be useful in highlighting regions of strain in the protein, including short hydrogen bonds and non-planar peptide groups.

    Organizational Affiliation: 

    Institute of Molecular Biology, Howard Hughes Medical Institute and Department of Physics, 1229 University of Oregon, Eugene, OR 97403-1229, USA.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Lysozyme
A
164Enterobacteria phage T4Mutation(s): 2 
Gene Names: E
EC: 3.2.1.17
Find proteins for P00720 (Enterobacteria phage T4)
Go to UniProtKB:  P00720
Small Molecules
Ligands 3 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
CL
Query on CL
Download SDF File 
Download CCD File 
A
CHLORIDE ION
Cl
VEXZGXHMUGYJMC-UHFFFAOYSA-M
 Ligand Interaction
RB
Query on RB
Download SDF File 
Download CCD File 
A
RUBIDIUM ION
Rb
NCCSSGKUIKYAJD-UHFFFAOYSA-N
 Ligand Interaction
BME
Query on BME
Download SDF File 
Download CCD File 
A
BETA-MERCAPTOETHANOL
C2 H6 O S
DGVVWUTYPXICAM-UHFFFAOYSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.06 Å
  • R-Value Free: 0.145 
  • R-Value Work: 0.120 
  • Space Group: P 32 2 1
Unit Cell:
Length (Å)Angle (°)
a = 60.199α = 90.00
b = 60.199β = 90.00
c = 95.242γ = 120.00
Software Package:
Software NamePurpose
TNTphasing
CCP4data scaling
MOSFLMdata reduction
TNTrefinement
SCALAdata scaling
SHELXL-97refinement
MAR345data collection

Structure Validation

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Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2004-11-30
    Type: Initial release
  • Version 1.1: 2008-04-30
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Version format compliance
  • Version 1.3: 2017-10-11
    Type: Refinement description
  • Version 1.4: 2018-01-31
    Type: Experimental preparation