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Analysis of nucleic acid double helix geometry

Title YEAST MATALPHA2/MCM1/DNA TERNARY TRANSCRIPTION COMPLEX CRYST STRUCTURE
PDB code 1MNM   (PDB summary)
NDB code PDR036 (NDB atlas)
Duplex length 25 base pairs
Protein Mating type alpha2/MCM1, Transcription factor, DNA binding domain: Helix-turn-helix, homeodomain

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 T4 A5 C6 C7 T8 A9 A10 T11 A12 G13 G14 G15 A16 A17 A18 T19 T20 T21 A22 C23 A24 C25 G26 3'
Strand 2    3' T52 A51 A50 T49 G48 G47 A46 T45 T44 A43 T42 C41 C40 C39 T38 T37 T36 A35 A34 A33 T32 G31 T30 G29 C28 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 T52            
    3.3 0.7 -0.6 32° -1°
T3 A51            
    3.4 -0.5 -0.5 28°
T4 A50            
    3.2 -0.2 1.1 41° -3°
A5 T49            
    3.4 -0.0 -0.5 30°
C6 G48            
    3.7 0.1 -0.3 37° -2°
C7 G47            
    3.7 1.2 0.1 39°
T8 A46            
    2.9 -1.6 0.8 39° -10° -2°
A9 T45            
    3.3 0.4 -0.2 38° -6° -2°
A10 T44            
    3.3 0.2 -0.4 33° -0°
T11 A43            
    3.5 -0.1 0.2 46° -7° -4°
A12 T42            
    3.5 0.6 0.0 32°
G13 C41            
    3.3 -1.2 0.1 38° -6°
G14 C40            
    3.3 -0.4 -0.1 34° 11°
G15 C39            
    3.4 0.2 0.3 34° 12°
A16 T38            
    3.1 0.9 -0.3 32° -4°
A17 T37            
    3.5 -0.2 -0.4 37° -5°
A18 T36            
    3.3 -0.5 -0.3 33° -4°
T19 A35            
    3.4 -0.2 0.1 32° -1°
T20 A34            
    3.1 -0.3 0.1 34°
T21 A33            
    3.5 0.9 0.5 42° -7°
A22 T32            
    3.0 -0.2 -0.4 29°
C23 G31            
    3.8 -0.1 -0.2 32° 16° -3°
A24 T30            
    3.1 -0.6 -0.5 30° -3°
C25 G29            
    3.2 0.3 0.6 38° -0°
G26 C28            


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 -117° A2 T52 -101° C2'-endo    
 -60°   -68° (BI)             -64° (BI)   44° 
    C2'-endo -109° T3 A51 -111° C2'-endo    
 33°   -76° (BI)             -90° (BI)   45° 
    C2'-endo -97° T4 A50 -97° C2'-endo    
 34°   51° (BII)             -18° (BI)   44° 
    C2'-endo -93° A5 T49 -109° C2'-endo    
 30°   -31° (BI)             -85° (BI)   48° 
    C2'-endo -99° C6 G48 -100° C2'-endo    
 43°   -37° (BI)             -60° (BI)   47° 
    C2'-endo -110° C7 G47 -108° C2'-endo    
 54°   -82° (BI)             42° (BII)   49° 
    C2'-endo -108° T8 A46 -88° C2'-endo    
 50°   77° (BII)             -70° (BI)   51° 
    C2'-endo -102° A9 T45 -111° C2'-endo    
 46°   -88° (BI)             -70° (BI)   57° 
    C2'-endo -102° A10 T44 -121° C2'-endo    
 57°   -75° (BI)             -82° (BI)   54° 
    C2'-endo -109° T11 A43 -115° C2'-endo    
 50°   -18° (BI)             -49° (BI)   62° 
    C2'-endo -110° A12 T42 -133° C2'-endo    
 50°   -62° (BI)             -2° (BI)   31° 
    C2'-endo -95° G13 C41 -96° C2'-endo    
 38°   61° (BII)             -45° (BI)   21° 
    C2'-endo -109° G14 C40 -100° C2'-endo    
 42°   -71° (BI)             -44° (BI)   9° 
    C2'-endo -96° G15 C39 -95° C2'-endo    
 36°   -90° (BI)             -31° (BI)   43° 
    C2'-endo -85° A16 T38 -105° C2'-endo    
 38°   -83° (BI)             -45° (BI)   39° 
    C2'-endo -105° A17 T37 -116° C2'-endo    
 45°   -62° (BI)             -55° (BI)   48° 
    C2'-endo -111° A18 T36 -113° C2'-endo    
 -63°   -47° (BI)             -96° (BI)   39° 
    C3'-exo -106° T19 A35 -105° C2'-endo    
 54°   -89° (BI)             -84° (BI)   40° 
    C2'-endo -108° T20 A34 -99° C2'-endo    
 -150°   4° (BI)             -76° (BI)   48° 
    C2'-endo -119° T21 A33 -115° C2'-endo    
 45°   -79° (BI)             35° (BII)   44° 
    C2'-endo -95° A22 T32 -102° C2'-endo    
 -78°   -50° (BI)             -88° (BI)   48° 
    C3'-exo -102° C23 G31 -106° C2'-endo    
 39°   -84° (BI)             -85° (BI)   -69° 
    C2'-endo -125° A24 T30 -103° C3'-exo    
 -1°   -36° (BI)             -62° (BI)   61° 
    C2'-endo -107° C25 G29 -110° C2'-endo    
 50°   -81° (BI)             -87° (BI)   -38° 
    C3'-exo -98° G26 C28 -134° 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