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model building with symmetry



Hye,

I would like to build a model for a dimere (the
2 molecules are 2-fold axis symmetry related).
I tried to duplicate the sequence of the monomere,
separated by a /:

>P1;acs
sequence:acs:.    :.:.    :.:?: : 3.66: 0.00
MESLKEMRKAQMSEGPAAILAIGTATPDNVFMQADYPDYYFRMTKSEHMTELKDKFRTLCEKSMIRKRHMCFSED
FLKANPEVCKHMGKSLNARQDIAVVETPRLGNEAALKAIKEWGQPKSSITHLIFCSSAGVDMPGADYQLTRILGL
NPSVKRMMIYQQGCYAGGTVVRLAKDLAENNKGSRVLVVCSELTAPTFRGPSPDAVDSLVGQALFADGAAALVVG
ADPDSSIERALYYLVSASQMLLPDSDGAIEGHIREEGLTVHLKKDVPALFSANIDTPLVEAFKPLGISDWNSIFW
IAHPGGPAILDQIEEKLGLKEDKLRASKHVMSEYGNMSSSCVLFVLDEMRSRSLQDGKSTTGQGLDWGVLFGFGP
GLTVETIVLRSVPIEA/
MESLKEMRKAQMSEGPAAILAIGTATPDNVFMQADYPDYYFRMTKSEHMTELKDKFRTLCEKSMIRKRHMCFSED
FLKANPEVCKHMGKSLNARQDIAVVETPRLGNEAALKAIKEWGQPKSSITHLIFCSSAGVDMPGADYQLTRILGL
NPSVKRMMIYQQGCYAGGTVVRLAKDLAENNKGSRVLVVCSELTAPTFRGPSPDAVDSLVGQALFADGAAALVVG
ADPDSSIERALYYLVSASQMLLPDSDGAIEGHIREEGLTVHLKKDVPALFSANIDTPLVEAFKPLGISDWNSIFW
IAHPGGPAILDQIEEKLGLKEDKLRASKHVMSEYGNMSSSCVLFVLDEMRSRSLQDGKSTTGQGLDWGVLFGFGP
GLTVETIVLRSVPIEA*

and create a known structure for each monomere of the template:

>P1;chs1
structureX:chs1:   1 : : 389 : :chalcone synthase: : 1.80: 0.00
MVSVSEIRKAQRAEGPATILAIGTANPANCVEQSTYPDFYFKITNSEHKTELKEKFQRMCDKSMIKRRYMYLTEE
ILKENPNVCEYMAPSLDARQDMVVVEVPRLGKEAAVKAIKEWGQPKSKITHLIVCTTSGVDMPGADYQLTKLLGL
RPYVKRYMMYQQGCFAGGTVLRLAKDLAENNKGARVLVVCSEVTAVTFRGPSDTHLDSLVGQALFGDGAAALIVG
SDPVPEIEKPIFEMVWTAQTIAPDSEGAIDGHLREAGLTFHLLKDVPGIVSKNITKALVEAFEPLGISDYNSIFW
IAHPGGPAILDQVEQKLALKPEKMNATREVLSEYGNMSSACVLFILDEMRKKSTQNGLKTTGEGLEWGVLFGFGP
GLTIETVVLRSVAI--/
---------------------------------------------------------------------------
---------------------------------------------------------------------------
---------------------------------------------------------------------------
---------------------------------------------------------------------------
---------------------------------------------------------------------------
----------------*
>P1;chs2
structureX:chs2:   1 : : 389 : :chalcone synthase: : 1.80: 0.00
---------------------------------------------------------------------------
---------------------------------------------------------------------------
---------------------------------------------------------------------------
---------------------------------------------------------------------------
---------------------------------------------------------------------------
----------------/
MVSVSEIRKAQRAEGPATILAIGTANPANCVEQSTYPDFYFKITNSEHKTELKEKFQRMCDKSMIKRRYMYLTEE
ILKENPNVCEYMAPSLDARQDMVVVEVPRLGKEAAVKAIKEWGQPKSKITHLIVCTTSGVDMPGADYQLTKLLGL
RPYVKRYMMYQQGCFAGGTVLRLAKDLAENNKGARVLVVCSEVTAVTFRGPSDTHLDSLVGQALFGDGAAALIVG
SDPVPEIEKPIFEMVWTAQTIAPDSEGAIDGHLREAGLTFHLLKDVPGIVSKNITKALVEAFEPLGISDYNSIFW
IAHPGGPAILDQVEQKLALKPEKMNATREVLSEYGNMSSACVLFILDEMRKKSTQNGLKTTGEGLEWGVLFGFGP
GLTIETVVLRSVAI--*

and run the model.top script:

> INCLUDE                             	# Include the predefined TOP routines
> SET ALNFILE  = 'acs.align'      	# alignment filename
> SET KNOWNS   = 'chs1' 'chs2'            # codes of the templates
> SET SEQUENCE = 'acs'            	# code of the target
> SET ATOM_FILES_DIRECTORY = '../../pdb/' # directories for input atom files
> SET STARTING_MODEL= 1               	# index of the first model 
> SET ENDING_MODEL  = 1               	# index of the last model
> CALL ROUTINE = 'model'              	# do homology modelling

and then I get the error:

> chkaln___> Checking pairwise structural superpositions: 
>            Equivalent CA pairs with distance difference larger than  6.0 angstroms:
> 
> ALN_POS TMPL1 TMPL2  RID1  RID2  NAM1  NAM2     DIST
> ----------------------------------------------------
> drmsq1__W> n<2
> drmsq3__W> n<2
> 
> chkaln___> Checking structure-sequence alignments: 
>            Implied target CA(i)-CA(i+1) distances longer than  8.0 angstroms:
> 
> ALN_POS  TMPL  RID1  RID2  NAM1  NAM2     DIST
> ----------------------------------------------
> 
> 
> << end of CHECK_ALIGNMENT.

fit2xyz_E> number of equivalent positions < 3:     0
recover__> MODELLER_STATUS >=  STOP_ON_ERROR:   1  1


I guess it certainly not the right way to do that. 
So, if somebody has any suggestion...

Thanks

Jean-Luc

------------------------------------
          Jean-Luc FERRER
   Structural Biology Laboratory
The Salk Institute for Biol. Studies
          P.O. Box 85800
 San Diego, California 92186-5800
               USA

phone: (619) 453-4100 ext 1535/1383
fax:   (619) 452-3683
email: 
------------------------------------