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CAPRI: Critical Assessment of PRediction of Interactions
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 MSD  CAPRI: Critical Assessment of PRediction of Interactions

First community wide experiment on the comparative evaluation of protein-protein docking for structure prediction

Hosted By EMBL/EBI-MSD Group

CAPRI Target 11 evaluation results

Raúl Méndez, Raphaël Leplae and Shoshana J. Wodak.
SCMBB Université Libre de Bruxelles, Cp 263, Brussels, Belgium.
Re-accessed on Friday January 07, 2005.

The evaluation results of the CAPRI Target 11 predictions are stored in different directories depending on the criteria that have been used. In the following the directories and their contents are briefly described.


Directory Information contains the information about Target 11, that was used in the evaluation and scoring. It contains the following files (file names are given in bold):

  • capri_11_xray.pdb: the crystal structure of the target (Target 11) in PDB format: cellulosome cohesin-dockerin complex.
    Dockerin molecule is homology modelled from 1DAQ while coordinates from the unbound structure 1ANU are taken for the cohesin.
  • capri_11_xray.B.contres: list of residue contacts in the target between subunit B of dockerin (considered as a Ligand) and subunit A of cellulosome Cohesin (considered as a Receptor).
  • capri_12_xray.B.intres: list of residues at the interface in the target between subunit B of dockerin (considered as a Ligand) and subunit A of cellulosome Cohesin (considered as a Receptor).
  • cc.capri_11_xray.B.d: list of clashes in the interface between dockerin and cohesin subunits.
    Final Summary

    File Target 11 Final Summary. summarizes all the information about the Target 11 evaluation in the same way as the corresponding summary file for target 01. It looks like that:

    PREDS			fnat		fnon-nat		 		fIR		 	INTERFACE RES.(OP)	IA(A2)		THETA ANGLE	DISTANCE	    Nclash		  L_rmsd	   I_rmsd
    								   Ligand    	Receptor  	   Ligand    	Receptor  
    T11_P01.7.B 0.182 0.828 0.684 0.629 0.650 0.815 739.8 72.2 12.529 11 15.481 3.493 T11_P01.9.B 0.145 0.822 0.526 0.314 0.588 0.500 680.4 130.7 18.973 35 21.346 4.344 T11_P01.6.B 0.127 0.865 0.526 0.771 0.667 0.931 681.6 84.5 13.999 30 16.669 3.781 T11_P01.1.B 0.091 0.894 0.632 0.657 0.667 0.821 689.6 115.2 11.615 38 16.952 4.288 T11_P01.10.B 0.091 0.898 0.526 0.629 0.714 0.846 576.3 115.2 16.125 39 20.309 4.760

    Again T11_P01.7.B means participant 01, prediction 7 for the Target 11, Ligand interface B (dockerin as Ligand and cohesin as Receptor).

    Column 2 gives the fraction of predicted contacts over native. This fraction is computed as the number of contacts in the prediction that match the contacts in the target, divided by the number of contacts in the target. As for target 01, 2 residues are considered as being in contact if at least one atom of one residue is within 5Å of an atoms of the other.

    Column 3 gives the fraction of non native predicted contacts (over prediction). This fraction is computed as the number of contacts in the prediction that don't match the contacts in the target, divided by the number of contacts in the prediction. This number accounts for the real efficiency of the prediction in term of contact: as bigger is the predicted interface as higher the probability of predict native contacts.

    Columns 4 and 5 list the interface residues ratios over native (fIR). Column 4 gives the ratio between the residues of the dockerin (Ligand) that are part of the interface in the prediction, over the the residues in the equivalent subunit in the target that are part of the interface in the target. The 5th column gives the same information for the residues in the cohesin (Receptor). All the interface residues lists are generated using the BRUGEL package, as the residues having ASA(unbound)- ASA(in the complex) > 0. Note that this time we don't use the Connolly algorithm. We compute the interface area for each pair of residues in contact using polygons instead of spherical cups, being this way less accurate but less demaning in terms of quality of the structure.

    Columns 6 and 7 lists the interface residue ratios over prediction. They are analogous to columns 4 and 5 but now dividing the number of residues in the prediction found in the target over the total number of provided residues at the predicted interface.

    Column 8 lists the interface Area (in Å2), calculated as the sum of interface areas per each pair of residues in contact implemented also in the BRUGEL package.

    Column 9 lists the rotation angle (Theta angle) necessary to fit the dockerin molecule in the predicted complex to that in the target, as for capri_11_xray.pdb. To compute this angle, we first perform a rigid-body fit (Kabsch, 1978, Acta. Cryst. A. 34, 827-828) on the cohesin (predicted cohesin onto the target cohesin) and apply the translation-rotation transformation to the whole predicted complex.

    After this first fit, a second fit is performed (starting from the previous situation)so as to superimpose the predicted "Ligand" molecules onto its closest counterpart in the target structure. The rotation angle corresponding to this second fitting is the listed theta angle.

    Column 10 lists the distance (in Angstroms) between geometric centers of predicted and target Ligand molecules before the second fit. The distance between the geometric centers together with the Theta angle give an idea of the global position of the Ligands in the prediction relative to the position in the target.

    Column 11 lists the number of clashes Nclash between the dockerin and the cohesin molecules for each predicted complex. Clashes are computed between heavy atoms within 3 Å . In the detailed information you can find the close contact pairs classified into three categories: from 0 to 1, from 1 to 2 and from 2 to 3 Å.

    Columns 12 and 13 list the RMSD's (Root Mean Square Deviation) values in Å . Column 11 list the RMSD values calculated between the Ligand's backbones once the corresponding Receptors are superimposed (Ligand RMSD or L_rmsd). Column 12 contains the rsmd's when sumperimposing the backbones of the residues at the interface on the prediction upon the counterpart in the target. Residues at the interface (Interface RMSD or I_rmsd) are re-defined here, as residues in the target having at least one atom within 10 Å of an atom of the other molecule. The equivalents for those residues in the predictions are considered as to be in the interface to sumperimpose. For all the RMSD calculations we consider the same molecular fragments as for the fits, but in the case of the interface RMSD's, restricted to the residues at the interface, according to this new definition.

    Contact List

    Directory ContactList contains one file per predicted interface, with information on the residue-residue contacts in the predicted versus the target complexes

    As an example the file T11_P12.6.B.highlighted is illustrated in part:

    Number of Contacts = 50 Matching List1 = 23/55

    B11   SER - A62   LYS
    B11   SER - A80   ALA
    B11   SER - A82   ASP
    B12   THR - A82   ASP
    B14   LEU - A62   LYS
    B14   LEU - A63   SER
    B14   LEU - A64   PHE
    B14   LEU - A65   ASP
    B14   LEU - A78   LEU
    B14   LEU - A80   ALA
    B15   THR - A65   ASP
    B17   LEU - A78   LEU
    B18   LYS - A65   ASP
    B18   LYS - A66   THR
    B18   LYS - A67   ALA
    B18   LYS - A78   LEU 1
    B21   VAL - A76   VAL 1

    Each predicted contact that matches the target contact list is highlighted with a number indicating the reference list is matching. For this round "1" refers to the only reference contact list, capri_11_xray.B.contres.


    Directory InterfaceResidues contains one file per predicted interface, with information on the residues forming the different interfaces in the prediction and how well they match those in the target interfaces.

    The information contained in each file is illustrated by an example, T11_P12.6.B.highlighted

    N_res_Ligand = 20 N_res_Receptor = 31 Match Ligand in List1 = 15/19 Matching Receptor in List1 = 28/35

    B11   SER
    B12   THR
    B14   LEU 1
    B15   THR
    B17   LEU
    B18   LYS 1
    . RECEPTOR LIST A31 ALA 1 A32 ASN 1 A33 CYS 1 A34 ASP 1

    Each time a residue of the dockerin (Ligand) or cohesin (Receptor) molecules in the predicted interface interface matches one of the interface residues in the target list, it is highlighted with the number of the corresponding target reference list. Analogously "1" stands for the only interface residue reference list capri_11_xray.B.intres.

    Note that interface residues list files and contact list ones are named the same (i.e. T11_P12.6.B.highlighted) but they are in different directories and their contents are completely different.


    Directory FittingSummary contains one file per predicted interface, with information on the results of fitting the predicted complex over the target complex. The information contained in each file is illustrated by an example, file T11_P12.6.B.fitting.summary

    Fitting of A prediction receptor Subunit onto X CAPRI receptor Subunit
    Rotation Matrix:
       0.47774  -0.41857  -0.77238
      -0.12913   0.83619  -0.53303
       0.86896   0.35439   0.34543
      Translation vector    -15.535   -50.098    13.271
    Fitting Ligands, B onto U
    Theta angle = 61.40
    Distance between geometric centres = 3.761028

    As for the evaluation of target 01, we give the information about the first fit (rotation matrix and translation vector including which subunits are involved), the distance between predicted dockerin and target dockerin after this first fit (considering just the fragment that is fitted in the second fit) and the Theta angle of the second fit.

    For this Target 11 evaluation, the first fit was made using the backbones of the common longest fragment between all cohesin subunits, residues 6-62, 68-86 and 90-142, while the second is made using the commong longest fragments of all the dockerin subunits, residues 10-13, 17-19 51, 53-54.In order to be consistent, the distance between geometric centres was calculated taking into account only this ligand fragment.

    Note that there is a big hinge affecting helix 2 on target dockerin compared to the one in 1DAQ proposed as a model for homology modeling. This is skipped from the fittings.

    Note that in order to not confuse chain ID's between target and predicted coordinate sets, the chain ID's in the target (capri_11_xray.pdb) were renamed as follows:

    A to X
    for the target cohesin and
    B to U
    for the target dockerin.


    Directory CloseContacts contains one file per predicted interface with information on the clashes in each predicted interface.

    For example part of file cc.T11_P12.6.B.d looks like that:

    Ligand Atom         Receptor Atom           Distance
    B 11   .SER.OG      A 82   .ASP.OD1         2.91
    B 45   .SER.O       A 32   .ASN.OD1         2.92
    B 45   .SER.OG      A 34   .ASP.OD1         2.93
    B 44   .ASN.ND2     A 118  .GLY.N           3.00

    As in the evaluation of target 01, the list of clashes is segregated into clashes between 0-1 (no contacts in this case), 1-2 (no contacts also) and 2-3Å. Empty files means, no close contacts found.