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Analysis of nucleic acid double helix geometry

Title HOMING ENDONUCLEASE I-CREI / DNA SUBSTRATE COMPLEX WITH CALCIUM
PDB code 1G9Y   (PDB summary)
NDB code PD0189 (NDB atlas)
Duplex length 24 base pairs
Protein Homing Endonuclease I-CreI, Nuclease

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' C401 G402 A403 A404 A405 C406 T407 G408 T409 C410 T411 C412 A413 C414 G415 A416 C417 G418 T419 T420 T421 T422 G423 C424 3'
Strand 2    3' G524 C523 T522 T521 T520 G519 A518 C517 A516 G515 A514 G513 T512 G511 C510 T509 G508 C507 A506 A505 A504 A503 C502 G501 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      

C401 G524            
    3.5 0.8 0.4 39° -3°
G402 C523            
    2.9 -1.7 0.8 34° -15°
A403 T522            
    3.0 0.7 -0.5 32° -1° -3°
A404 T521            
    3.6 -0.2 -0.6 35° -6°
A405 T520            
    3.4 -0.2 -0.0 33° -5°
C406 G519            
    3.4 0.1 -0.3 29° 10° -1°
T407 A518            
    3.9 0.4 -0.4 30° 18°
G408 C517            
    3.5 0.3 -0.4 28°
T409 A516            
    3.7 -1.0 0.2 36° -0°
C410 G515            
    2.9 0.8 0.1 30°
T411 A514            
    3.3 0.4 -0.9 28° -7°
C412 G513            
    3.7 0.0 1.5 59° -14° -3°
A413 T512            
    3.9 -0.5 -0.9 23° -8° -1°
C414 G511            
    2.7 -0.9 0.1 32° 10° -2°
G415 C510            
    3.6 0.6 0.4 37° -0°
A416 T509            
    3.6 -0.2 -0.4 30° -0° -1°
C417 G508            
    3.8 -0.3 -0.4 32° 18° -2°
G418 C507            
    3.5 -0.1 0.2 32° 13°
T419 A506            
    3.6 -0.3 -0.1 36° -0°
T420 A505            
    3.4 -0.1 -0.5 32° -3°
T421 A504            
    3.1 0.1 -0.4 31°
T422 A503            
    3.1 0.4 0.5 38°
G423 C502            
    3.0 -0.4 0.3 29° -1°
C424 G501            


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 -136° C401 G524 -100° C2'-endo    
 49°   -75° (BI)             63° (BII)   44° 
    C2'-endo -89° G402 C523 -72° C2'-endo    
 47°   14° (BI)             -75° (BI)   49° 
    C2'-endo -105° A403 T522 -106° C2'-endo    
 28°   -105° (BI)             -65° (BI)   45° 
    C2'-endo -94° A404 T521 -116° C2'-endo    
 46°   -98° (BI)             -96° (BI)   43° 
    C2'-endo -119° A405 T520 -116° C2'-endo    
 50°   -65° (BI)             -64° (BI)   40° 
    C2'-endo -115° C406 G519 -108° C2'-endo    
 19°   -91° (BI)             -84° (BI)   44° 
    C2'-endo -94° T407 A518 -143° C2'-endo    
 42°   -75° (BI)             -70° (BI)   177° 
    C2'-endo -117° G408 C517 -166° C4'-exo    
 46°   -56° (BI)             -102° (BI)   40° 
    C2'-endo -115° T409 A516 -99° C1'-exo    
 42°   53° (BII)             -64° (BI)   158° 
    C2'-endo -117° C410 G515 -124° C1'-exo    
 44°   -69° (BI)             167° (BII)   173° 
    C2'-endo -91° T411 A514 -155° C2'-endo    
 169°   -60° (BI)             -98° (BI)   54° 
    C2'-endo -160° C412 G513 -80° C2'-endo    
 54°   -31° (BI)             -61° (BI)   156° 
    C2'-endo -75° A413 T512 -175° C2'-endo    
 -180°   -88° (BI)             -58° (BI)   42° 
    C2'-endo -164° C414 G511 -86° C2'-endo    
 151°   151° (BII)             -82° (BI)   52° 
    C1'-exo -121° G415 C510 -113° C2'-endo    
 42°   -75° (BI)             -7° (BI)   49° 
    C2'-endo -91° A416 T509 -119° C2'-endo    
 174°   -102° (BI)             -63° (BI)   46° 
    C3'-endo -164° C417 G508 -115° C2'-endo    
 54°   -67° (BI)             -71° (BI)   41° 
    C2'-endo -142° G418 C507 -107° C1'-exo    
 53°   -73° (BI)             -82° (BI)   -67° 
    C2'-endo -113° T419 A506 -111° C3'-exo    
 43°   -84° (BI)             -51° (BI)   49° 
    C2'-endo -118° T420 A505 -118° C2'-endo    
 45°   -78° (BI)             -96° (BI)   41° 
    C2'-endo -114° T421 A504 -107° C1'-exo    
 -78°   -47° (BI)             -76° (BI)   48° 
    C3'-exo -128° T422 A503 -102° C2'-endo    
 41°   -83° (BI)             -41° (BI)   50° 
    C2'-endo -88° G423 C502 -112° C1'-exo    
 50°   -14° (BI)             -29° (BI)   53° 
    C2'-endo -95° C424 G501 -86° 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