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Analysis of nucleic acid double helix geometry

Title THE CRYSTAL STRUCTURE OF THE ESTROGEN RECEPTOR DNA-BINDING DOMAIN BOUND TO DNA: HOW RECEPTORS DISCRIMINATE BETWEEN THEIR RESPONSE ELEMENTS
PDB code 1HCQ   (PDB summary)
NDB code PDRC03 (NDB atlas)
Duplex length 17 base pairs
Protein Estrogen receptor, Transcription factor, DNA binding domain: Cys4 zinc finger, nuclear receptor type

Only the nucleic acid double helix part of the structure is analysed here. Small ligands, proteins, and overhanging ends are not taken into account. Information on the complete structure is available at the Image Library Entry page and at the Sequence, Chains, Units page.

Strand 1    5' C2 A3 G4 G5 T6 C7 A8 C9 A10 G11 T12 G13 A14 C15 C16 T17 G18 3'
Strand 2    3' G36 T35 C34 C33 A32 G31 T30 G29 T28 C27 A26 C25 T24 G23 G22 A21 C20 5'

Side view 1 Top view
Side view 1 Top view
Side view 2 3-dimensional interactive models
(Help)
  

RASMOL, CHIME, VRML 2.0, PDB

Side view 2  

Figure 1   Three orthogonal views of the double helix (Help). Residues are colored according to the nucleotide type (Help: Color codes). The curvilinear helical axis (green) was calculated with CURVES. The double helix is oriented with respect to the principle axis of inertia of the curvilinear helical axis (see Help for further explanations). This drawing reveals immediately if there is any bending of the helical axis.


Analysis of helical axis bending


Inter base pair parameters

The six inter base pair parameters (rise, shift, slide, twist, roll, tilt) describe the translational and rotational displacement between neighbouring base pairs. See Help for further explanations.

Plot of inter base pair parameters with respect to global and local helical axes:  PDF,   GIF
(Global parameters from CURVES,  local parameters from CURVES and FREEHELIX)

Table 1.  Inter base pair parameters with respect to the global helical axis, calculated with CURVES.


  Strand 1      Strand 2        riseg          shiftg          slideg          twistg         rollg         tiltg    
    / Å / Å / Å      

C2 G36            
    3.2 -0.2 0.3 37° -4°
A3 T35            
    3.4 0.3 -0.1 31°
G4 C34            
    3.7 0.2 -0.6 42° -4°
G5 C33            
    3.4 -0.2 -0.6 31°
T6 A32            
    3.3 0.5 0.6 38°
C7 G31            
    3.5 -0.8 0.8 34° -5°
A8 T30            
    3.4 0.3 -1.1 31° -0°
C9 G29            
    3.5 0.3 0.3 50°
A10 T28            
    3.3 -0.4 -0.3 30° -3°
G11 C27            
    3.5 -0.2 -1.0 28° -3°
T12 A26            
    3.4 0.7 1.0 40°
G13 C25            
    3.4 -0.7 0.7 38° -2° -3°
A14 T24            
    3.2 0.1 -0.7 28° -0°
C15 G23            
    3.8 -0.0 -0.7 42°
C16 G22            
    3.4 -0.7 -0.1 35° -3°
T17 A21            
    3.0 0.7 0.4 34° -2°
G18 C20            


Backbone parameters

Table 2.  Selected torsional angles and sugar pucker phase angles describing the conformation of the sugar phosphate backbone. (See Help for further explanations.)


 gamma     epsilon-zeta       pucker        chi      Strand 1     Strand 2      chi        pucker       epsilon-zeta     gamma 

    C1'-exo -139° C2 G36 -100° C2'-endo    
 81°   -56° (BI)             -53° (BI)   -37° 
    C2'-endo -109° A3 T35 -97° C3'-exo    
 48°   -94° (BI)             -21° (BI)   -64° 
    C1'-exo -109° G4 C34 -113° C3'-exo    
 -79°   -21° (BI)             -71° (BI)   65° 
    C3'-exo -121° G5 C33 -146° O1'-endo    
 58°   -76° (BI)             -91° (BI)   50° 
    C1'-exo -112° T6 A32 -105° C1'-exo    
 38°   -56° (BI)             54° (BII)   54° 
    C2'-endo -75° C7 G31 -92° C2'-endo    
 51°   38° (BII)             -78° (BI)   65° 
    C3'-exo -91° A8 T30 -132° O1'-endo    
 51°   -70° (BI)             -54° (BI)   65° 
    O1'-endo -126° C9 G29 -110° C2'-endo    
 59°   -56° (BI)             -80° (BI)   65° 
    C2'-endo -103° A10 T28 -119° O1'-endo    
 59°   -29° (BI)             -94° (BI)   62° 
    C2'-endo -114° G11 C27 -141° O1'-endo    
 64°   -73° (BI)             -65° (BI)   33° 
    O1'-endo -132° T12 A26 -90° C3'-exo    
 69°   -85° (BI)             65° (BII)   29° 
    C2'-endo -94° G13 C25 -72° C2'-endo    
 36°   70° (BII)             -44° (BI)   3° 
    C2'-endo -96° A14 T24 -105° C2'-endo    
 13°   -26° (BI)             -64° (BI)   35° 
    C2'-endo -102° C15 G23 -132° C1'-exo    
 52°   11° (BI)             -0° (BI)   46° 
    C1'-exo -140° C16 G22 -98° C2'-endo    
 70°   -99° (BI)             -41° (BI)   52° 
    C2'-endo -112° T17 A21 -89° C3'-exo    
 55°   -55° (BI)             -36° (BI)   53° 
    C1'-exo -111° G18 C20 -133° C1'-exo    


Groove width

Plot of minor groove width:   PDF,   GIF
Plot of major groove width:   PDF,   GIF
(See Help for further explanations.)

Further information

Full output from CURVES  (helical parameters with respect to global and local axes)

Full output from FREEHELIX  (helical parameters with respect to local axis, angles between normal vectors)

Chirality of ribose and phosphate atoms
Check the naming of phosphate and ribose substituents. Recommended for phosphate oxygens and for ribose hydrogens in NMR structures.


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Perl script:    helixparameter.pl  (15 Sep 2016)
Author:    Peter Slickers  (slickers@leibniz-fli.de),  IMB Jena,  Germany