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Analysis of nucleic acid double helix geometry

Title CRYSTAL STRUCTURE OF THE INTEIN HOMING ENDONUCLEASE PI-SCEI BOUND TO ITS SUBSTRATE DNA (CA2+ FREE)
PDB code 1LWT   (PDB summary)
NDB code PD0320 (NDB atlas)
Duplex length 36 base pairs
Protein Endonuclease PI-SceI, Nuclease, DNA binding domain: Alpha-helix|beta-barrel, DNA binding domain: Basic helix-loop-helix leucine zipper|helix-turn-helix, POU domain|high mobility group|zinc finger

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' T2 C3 T4 A5 T6 G7 T8 C9 G10 G11 G12 T13 G14 C15 G16 G17 A18 G19 A20 A21 A22 G23 A24 G25 G26 T27 A28 A29 T30 G31 A32 A33 A34 T35 G36 G37 3'
Strand 2    3' A37 G36 A35 T34 A33 C32 A31 G30 C29 C28 C27 A26 C25 G24 C23 C22 T21 C20 T19 T18 T17 C16 T15 C14 C13 A12 T11 T10 A9 C8 T7 T6 T5 A4 C3 C2 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      

T2 A37            
    3.6 -0.1 -0.1 32° 12° -9°
C3 G36            
    3.5 -0.1 -1.0 33°
T4 A35            
    3.1 0.8 1.0 46° -2°
A5 T34            
    3.5 -0.3 -0.2 33° -4°
T6 A33            
    3.2 -0.1 0.2 37°
G7 C32            
    3.5 0.2 -0.8 29° 10° -2°
T8 A31            
    3.5 -0.3 -0.4 36° -2°
C9 G30            
    3.0 0.2 0.6 37° -1°
G10 C29            
    3.3 0.2 -0.2 34°
G11 C28            
    3.3 0.6 0.3 42° -4°
G12 C27            
    3.6 0.5 -0.9 33° -3°
T13 A26            
    4.0 -0.5 1.5 52° -22° -2°
G14 C25            
    3.8 -0.1 -0.3 30° -5°
C15 G24            
    3.1 0.0 0.7 38° -19° -10°
G16 C23            
    4.9 0.1 0.0 19° 28°
G17 C22            
    3.1 -0.3 0.2 31° -1° -5°
A18 T21            
    3.1 -0.2 -0.1 31° -5°
G19 C20            
    3.1 -0.1 -0.8 33°
A20 T19            
    3.6 0.2 0.2 42° -6° -4°
A21 T18            
    3.2 -0.3 0.5 35° -8° -2°
A22 T17            
    3.6 0.2 -0.2 36° -1°
G23 C16            
    3.4 -0.7 -0.3 31° 15° -2°
A24 T15            
    2.7 0.1 0.2 36° -1° -4°
G25 C14            
    3.9 0.1 -0.3 38°
G26 C13            
    3.4 -0.5 -0.6 28° -7° -3°
T27 A12            
    3.1 0.2 0.9 37° -1°
A28 T11            
    3.6 -0.0 -0.4 33°
A29 T10            
    3.1 0.1 -0.8 34° -1° -1°
T30 A9            
    3.6 0.3 1.1 36°
G31 C8            
    3.0 0.1 -0.7 20° 18° -6°
A32 T7            
    3.1 0.1 0.5 39° -8° -2°
A33 T6            
    3.6 -0.4 -0.2 37° -4° -5°
A34 T5            
    3.2 -0.5 -0.6 31°
T35 A4            
    2.9 0.3 0.6 32° -0°
G36 C3            
    3.6 -0.0 -0.3 33°
G37 C2            


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 

    C3'-exo -102° T2 A37 -79° C2'-endo    
 56°   -93° (BI)             -66° (BI)   -76° 
    C2'-endo -110° C3 G36 -128° C3'-exo    
 -60°   -54° (BI)             -55° (BI)   67° 
    C3'-exo -123° T4 A35 -104° C3'-exo    
 161°   -86° (BI)             36° (BII)   52° 
    C2'-endo -118° A5 T34 -79° C2'-endo    
 -64°   -44° (BI)             -73° (BI)   51° 
    C3'-exo -115° T6 A33 -92° C3'-exo    
 173°   -87° (BI)             -68° (BI)   -52° 
    C3'-exo -136° G7 C32 -94° C3'-exo    
 26°   -10° (BI)             -60° (BI)   33° 
    C2'-endo -85° T8 A31 -91° C2'-endo    
 -32°   156° (BII)             -124° (BI)   43° 
    C3'-exo -103° C9 G30 -90° C2'-endo    
 39°   -63° (BI)             -49° (BI)   32° 
    C3'-exo -85° G10 C29 -90° C2'-endo    
 52°   -107° (BI)             -92° (BI)   43° 
    C3'-exo -90° G11 C28 -97° C2'-endo    
 60°   -41° (BI)             -34° (BI)   25° 
    C2'-endo -91° G12 C27 -102° C2'-endo    
 -22°   117° (BII)             -76° (BI)   53° 
    C3'-exo -91° T13 A26 -75° C3'-exo    
 60°   94° (BII)             95° (BII)   31° 
    C3'-exo -99° G14 C25 -65° C2'-endo    
 33°   -99° (BI)             -23° (BI)   51° 
    C2'-endo -82° C15 G24 -72° C3'-exo    
 61°   -62° (BI)             -39° (BI)   11° 
    C3'-exo -70° G16 C23 -67° C3'-exo    
 -67°   -42° (BI)             -75° (BI)   -32° 
    C3'-exo -86° G17 C22 -59° C3'-exo    
 -35°   -57° (BI)             114° (BII)   -21° 
    C3'-exo -85° A18 T21 -70° C2'-endo    
 22°   -57° (BI)             -46° (BI)   -57° 
    C2'-endo -88° G19 C20 -104° C3'-exo    
 42°   -137° (BI)             -53° (BI)   -145° 
    C3'-exo -73° A20 T19 -123° C2'-endo    
 53°   -107° (BI)             121° (BII)   58° 
    C3'-exo -95° A21 T18 -92° C2'-endo    
 60°   -114° (BI)             -125° (BI)   -72° 
    C2'-endo -80° A22 T17 -130° C3'-exo    
 -87°   -7° (BI)             -38° (BI)   28° 
    C3'-exo -125° G23 C16 -95° C2'-endo    
 31°   -90° (BI)             -88° (BI)   53° 
    C2'-endo -112° A24 T15 -95° C3'-exo    
 68°   -60° (BI)             -76° (BI)   47° 
    C2'-endo -117° G25 C14 -99° C2'-endo    
 48°   -65° (BI)             -124° (BI)   -88° 
    C3'-exo -111° G26 C13 -120° C3'-exo    
 -62°   -54° (BI)             -51° (BI)   44° 
    C3'-exo -111° T27 A12 -86° C2'-endo    
 -102°   -30° (BI)             -85° (BI)   34° 
    C3'-exo -124° A28 T11 -100° C3'-exo    
 38°   -119° (BI)             -111° (BI)   30° 
    C2'-endo -93° A29 T10 -93° C2'-endo    
 -58°   -69° (BI)             -88° (BI)   57° 
    C3'-exo -111° T30 A9 -110° C2'-endo    
 37°   -63° (BI)             -9° (BI)   -67° 
    C2'-endo -87° G31 C8 -77° C3'-exo    
 -63°   -47° (BI)             -36° (BI)   43° 
    C2'-endo -98° A32 T7 -99° C2'-endo    
 39°   170° (BII)             -95° (BI)   -83° 
    C3'-exo -94° A33 T6 -114° C3'-exo    
 49°   -59° (BI)             -67° (BI)   -100° 
    C2'-endo -112° A34 T5 -142° C3'-exo    
 -62°   -32° (BI)             -17° (BI)   35° 
    C3'-exo -97° T35 A4 -72° C2'-endo    
 -52°   -45° (BI)             -68° (BI)   36° 
    C3'-exo -89° G36 C3 -111° C3'-exo    
 -77°   -60° (BI)             -100° (BI)   50° 
    C3'-exo -114° G37 C2 -121° 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