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Analysis of nucleic acid double helix geometry

Title NMR STRUCTURE OF THE MU BACTERIOPHAGE REPRESSOR DNA-BINDING DOMAIN/DNA COMPLEX
PDB code 1G4D   (PDB summary)
NDB code 1G4D (NDB atlas)
Duplex length 16 base pairs
Protein Mu Repressor, Transcription Factor, DNA binding domain: Alpha-helix, DNA binding domain: Helix-turn-helix

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' C102 C103 T104 T105 T106 T107 C108 A109 G110 T111 A112 A113 T114 C115 T116 G117 3'
Strand 2    3' G135 G134 A133 A132 A131 A130 G129 T128 C127 A126 T125 T124 A123 G122 A121 C120 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      

C102 G135            
    4.0 0.2 0.1 35° -10°
C103 G134            
    3.9 -0.6 -0.2 30° -1°
T104 A133            
    3.2 0.4 0.2 31°
T105 A132            
    3.5 -0.2 0.1 35° -0°
T106 A131            
    3.8 0.1 0.1 33° -1° -2°
T107 A130            
    3.7 -0.1 -0.6 30° 14°
C108 G129            
    3.3 0.2 0.3 42° -2°
A109 T128            
    3.9 -0.8 -0.1 23°
G110 C127            
    3.5 0.8 -0.1 30° -3° -1°
T111 A126            
    3.0 -0.3 -0.0 41° -3°
A112 T125            
    3.3 -0.1 0.3 34° -8°
A113 T124            
    4.0 0.1 -0.4 35° -4°
T114 A123            
    3.2 -0.2 -0.4 29° 13° -0°
C115 G122            
    3.2 0.1 0.1 32° -6°
T116 A121            
    4.0 0.0 -0.1 35° 16°
G117 C120            


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 -140° C102 G135 -116° C1'-exo    
 64°   -94° (BI)             -86° (BI)   42° 
    C1'-exo -125° C103 G134 -116° C1'-exo    
 39°   -102° (BI)             -100° (BI)   43° 
    O1'-endo -113° T104 A133 -110° C1'-exo    
 61°   -107° (BI)             -106° (BI)   36° 
    C1'-exo -120° T105 A132 -110° C2'-endo    
 44°   -82° (BI)             -99° (BI)   45° 
    O1'-endo -115° T106 A131 -120° C1'-exo    
 59°   -100° (BI)             -96° (BI)   33° 
    C1'-exo -121° T107 A130 -115° C1'-exo    
 43°   -105° (BI)             -107° (BI)   38° 
    C1'-exo -119° C108 G129 -115° C2'-endo    
 39°   -101° (BI)             -44° (BI)   138° 
    C1'-exo -112° A109 T128 -151° C1'-exo    
 28°   -85° (BI)             -92° (BI)   30° 
    C4'-exo -114° G110 C127 -115° O1'-endo    
 84°   -105° (BI)             -100° (BI)   42° 
    C1'-exo -138° T111 A126 -113° C1'-exo    
 40°   -104° (BI)             -105° (BI)   63° 
    C1'-exo -115° A112 T125 -126° C1'-exo    
 70°   -103° (BI)             -101° (BI)   39° 
    C1'-exo -125° A113 T124 -124° C1'-exo    
 40°   -104° (BI)             -93° (BI)   33° 
    C1'-exo -121° T114 A123 -120° C1'-exo    
 32°   -101° (BI)             -98° (BI)   41° 
    C1'-exo -117° C115 G122 -118° C1'-exo    
 77°   -100° (BI)             -92° (BI)   46° 
    C1'-exo -129° T116 A121 -119° C1'-exo    
 35°   -68° (BI)             -113° (BI)   43° 
    C1'-exo -112° G117 C120 -128° C3'-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