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Analysis of nucleic acid double helix geometry

Title CRYSTAL STRUCTURE OF TRIMERIC CRE RECOMBINASE-LOX COMPLEX
PDB code 1DRG   (PDB summary)
NDB code PD0113 (NDB atlas)
Duplex length 15 base pairs
Protein Cre recombinase, Recombinase

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' A2 T3 A4 A5 C6 T7 T8 C9 G10 T11 A12 T13 A14 G15 C16 3'
Strand 2    3' T19 A18 T17 T16 G15 A14 A13 G12 C11 A10 T9 A8 T7 C6 G5 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      

A2 T19            
    3.3 -0.5 -0.8 28° -4°
T3 A18            
    3.3 -0.2 1.1 40° -6° -1°
A4 T17            
    3.0 0.5 0.0 28° -7°
A5 T16            
    3.6 0.4 -1.0 28° -1° -2°
C6 G15            
    3.7 -0.1 -0.2 40° 10° -2°
T7 A14            
    3.0 -0.1 0.1 37° -1°
T8 A13            
    3.1 -0.2 -0.6 30°
C9 G12            
    3.3 0.1 1.0 37° -4°
G10 C11            
    3.1 -0.3 0.1 26° -3°
T11 A10            
    3.5 0.3 -0.4 38°
A12 T9            
    3.4 0.7 -0.3 32° -2°
T13 A8            
    3.8 -0.6 0.3 42° -6°
A14 T7            
    3.3 -0.1 -0.0 36° -1°
G15 C6            
    3.7 0.1 0.1 30° -1° -3°
C16 G5            


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 

    C4'-endo -88° A2 T19 -157° C2'-endo    
 41°   -80° (BI)             -131° (BI)   27° 
    O1'-endo -124° T3 A18 -102° C1'-exo    
 60°   -60° (BI)             -9° (BI)   -102° 
    C2'-endo -98° A4 T17 -121° C3'-exo    
 27°   -69° (BI)             -51° (BI)   81° 
    C2'-endo -90° A5 T16 -127° C1'-exo    
 153°   -75° (BI)             -90° (BI)   34° 
    C4'-exo -175° C6 G15 -114° C2'-endo    
 70°   -82° (BI)             -38° (BI)   11° 
    C2'-endo -127° T7 A14 -92° C2'-endo    
 35°   -57° (BI)             27° (BII)   25° 
    C2'-endo -104° T8 A13 -90° C2'-endo    
 -42°   -55° (BI)             -58° (BI)   50° 
    C2'-endo -94° C9 G12 -97° C2'-endo    
 25°   -28° (BI)             63° (BII)   42° 
    C2'-endo -94° G10 C11 -81° C2'-endo    
 43°   -24° (BI)             -97° (BI)   35° 
    C2'-endo -102° T11 A10 -96° C3'-exo    
 59°   -77° (BI)             -102° (BI)   77° 
    C1'-exo -120° A12 T9 -132° C2'-endo    
 41°   -74° (BI)             -104° (BI)   66° 
    C1'-exo -110° T13 A8 -150° C4'-exo    
 60°   11° (BI)             -49° (BI)   21° 
    C2'-endo -134° A14 T7 -96° C2'-endo    
 20°   -54° (BI)             -68° (BI)   48° 
    C2'-endo -105° G15 C6 -117° C1'-exo    
 106°   -73° (BI)             -53° (BI)   61° 
    C1'-exo -148° C16 G5 -106° C2'-endo    


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