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Analysis of nucleic acid double helix geometry

Title METHIONINE REPRESSOR MUTANT (Q44K) PLUS COREPRESSOR (S- ADENOSYL METHIONINE) COMPLEXED TO A CONSENSUS OPERATOR SEQUENCE
PDB code 1MJ2   (PDB summary)
NDB code PD0173 (NDB atlas)
Duplex length 18 base pairs
Protein Methionine repressor, Transcription factor, DNA binding domain: Met repressor beta-sheet

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' T0 A1 G2 A3 C4 G5 T6 C7 T8 A9 G10 A11 C12 G13 T14 C15 T16 A17 3'
Strand 2    3' A17 T16 C15 T14 G13 C12 A11 G10 A9 T8 C7 T6 G5 C4 A3 G2 A1 T0 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      

T0 A17            
    3.3 -0.3 0.6 40° -2° -7°
A1 T16            
    3.3 0.4 -0.8 29°
G2 C15            
    3.1 -0.6 0.1 34° -6°
A3 T14            
    3.2 0.2 -0.6 34° -0°
C4 G13            
    3.5 -0.2 0.5 35°
G5 C12            
    3.1 0.2 -0.5 30° -3°
T6 A11            
    3.2 0.5 -0.1 38°
C7 G10            
    3.4 -0.7 -0.5 25° -2°
T8 A9            
    3.5 0.1 0.7 48° -7°
A9 T8            
    3.4 0.3 -0.5 32° -1°
G10 C7            
    3.2 -0.3 -0.1 34° -2° -3°
A11 T6            
    3.2 -0.3 -0.4 32°
C12 G5            
    3.4 0.3 0.7 36°
G13 C4            
    3.2 -0.5 -0.6 33° -1° -2°
T14 A3            
    3.4 0.7 0.0 34°
C15 G2            
    3.2 -0.3 -0.9 25°
T16 A1            
    3.2 0.3 0.6 39° -2° -0°
A17 T0            


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 

    C2'-endo -102° T0 A17 -83° C2'-endo    
 55°   10° (BI)             -34° (BI)   44° 
    C2'-endo -113° A1 T16 -113° C2'-endo    
 32°   -74° (BI)             -13° (BI)   26° 
    C1'-exo -95° G2 C15 -95° C2'-endo    
 47°   17° (BI)             -30° (BI)   41° 
    C2'-endo -123° A3 T14 -105° C2'-endo    
 10°   -75° (BI)             -74° (BI)   46° 
    C2'-endo -98° C4 G13 -111° C2'-endo    
 34°   12° (BI)             -35° (BI)   3° 
    C2'-endo -103° G5 C12 -90° C2'-endo    
 40°   -60° (BI)             -70° (BI)   37° 
    C2'-endo -107° T6 A11 -112° C2'-endo    
 20°   -62° (BI)             -27° (BI)   45° 
    C2'-endo -96° C7 G10 -107° C1'-exo    
 57°   -53° (BI)             -101° (BI)   48° 
    C2'-endo -119° T8 A9 -105° C2'-endo    
 52°   -51° (BI)             -48° (BI)   45° 
    C2'-endo -102° A9 T8 -109° C2'-endo    
 36°   -92° (BI)             -41° (BI)   43° 
    C1'-exo -106° G10 C7 -110° C2'-endo    
 42°   -45° (BI)             -46° (BI)   42° 
    C2'-endo -106° A11 T6 -108° C2'-endo    
 15°   -71° (BI)             -90° (BI)   37° 
    C2'-endo -93° C12 G5 -106° C2'-endo    
 39°   -43° (BI)             -24° (BI)   6° 
    C2'-endo -105° G13 C4 -94° C2'-endo    
 41°   -92° (BI)             -88° (BI)   45° 
    C2'-endo -110° T14 A3 -124° C2'-endo    
 21°   -49° (BI)             16° (BI)   32° 
    C2'-endo -103° C15 G2 -96° C1'-exo    
 45°   -63° (BI)             -79° (BI)   53° 
    C1'-exo -113° T16 A1 -105° C2'-endo    
 38°   -2° (BI)             -6° (BI)   49° 
    C2'-endo -94° A17 T0 -104° 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