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Re: [modeller_usage] modeller_usage Digest, Vol 10, Issue 69



Dear SCHWARZ,
Salign alterations won't help much, as such all the times. Some improvements in TBM-HA modeling can be achieved with some alteration of few parameters as the best set applied, over the default MODELLER set of parameters, and that too only when you have enough coordinate information available for a target sequence. But if you think to change (heartly as Benn said), think of augmented improvement of each parameter with the another alteration. 

Ashish

Ashish Runthala,
Lecturer, Structural Biology Cell,
Biological Sciences Group,
BITS, Pilani
Rajasthan, INDIA

----- Original Message -----
From: "modeller usage-request" <>
To: "modeller usage" <>
Sent: Wednesday, April 13, 2011 8:26:21 PM GMT +05:30 Chennai, Kolkata, Mumbai, New Delhi
Subject: modeller_usage Digest, Vol 10, Issue 69

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Today's Topics:

   1. Re: How Alignment Score is calculated. (Modeller Caretaker)
   2. modifiable version of	salign.iterative_structural_align()
      (Benjamin SCHWARZ)
   3. Re: modifiable version	of	salign.iterative_structural_align()
      (Modeller Caretaker)
   4. Modelling a protein loop close to DNA ..... (Sergio Garay)


----------------------------------------------------------------------

Message: 1
Date: Mon, 11 Apr 2011 10:16:57 -0700
From: Modeller Caretaker <>
Subject: Re: [modeller_usage] How Alignment Score is calculated.
To: Ashish Runthala <>
Cc: modeller <>
Message-ID: <>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

On 04/09/2011 10:00 PM, Ashish Runthala wrote:
> When pairwise alignment score calculated by MODELLER
> is not parallel to the Model Accuracy. Then what is the benefit
> Alignment Score holds for? Benn, will you please tell me the formula
> for calculating Alignment Score for a pairwise alignment. What is the
> matrix it uses for alignment and score computation. How it is
> calculated.

The alignment score is simply the sum of residue-residue distances and 
gap penalties from tracing the path that dynamic programming finds 
through the alignment matrix.

In general, alignment scores are a poor predictor of model quality. I'm 
not aware of any claims to the contrary in the Modeller documentation.

	Ben Webb, Modeller Caretaker
-- 
             http://www.salilab.org/modeller/
Modeller mail list: http://salilab.org/mailman/listinfo/modeller_usage


------------------------------

Message: 2
Date: Tue, 12 Apr 2011 16:27:40 +0200
From: Benjamin SCHWARZ <>
Subject: [modeller_usage] modifiable version of
	salign.iterative_structural_align()
To: modeller <>
Message-ID: <>
Content-Type: text/plain; charset=us-ascii

Hi list,

    If I understand well, the salign.iterative_structural_align() function is an exact implementation of the algorithm presented in [Madhusudhan2009]. Is there a python script version of this function ? Something that could be tweaked and modified...

    --Ben.S


------------------------------

Message: 3
Date: Tue, 12 Apr 2011 09:11:00 -0700
From: Modeller Caretaker <>
Subject: Re: [modeller_usage] modifiable version	of
	salign.iterative_structural_align()
To: Benjamin SCHWARZ <>
Cc: modeller <>
Message-ID: <>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

On 4/12/11 7:27 AM, Benjamin SCHWARZ wrote:
> If I understand well, the salign.iterative_structural_align()
> function is an exact implementation of the algorithm presented in
> [Madhusudhan2009]. Is there a python script version of this function
> ? Something that could be tweaked and modified...

Of course - all the Modeller scripts are Python scripts, so you can 
modify them to your heart's content. Look at modlib/modeller/salign.py.

	Ben Webb, Modeller Caretaker
-- 
             http://www.salilab.org/modeller/
Modeller mail list: http://salilab.org/mailman/listinfo/modeller_usage


------------------------------

Message: 4
Date: Wed, 13 Apr 2011 07:09:59 -0400
From: Sergio Garay <>
Subject: [modeller_usage] Modelling a protein loop close to DNA .....
To: 
Message-ID: <BANLkTimgaTV=x3+>
Content-Type: text/plain; charset="iso-8859-1"

Hi all

I have obtained a reasonably good model of protein dimer close to a DNA
molecule just copying the DNA template into my target. But now I want to
refine a protein loop close to DNA molecule but taking into account all
"real" interactions between the atoms of my protein and DNA. At the moment I
was not able to make modeller to recognize my target dna bases. So, my
question is: if the ordering of the DNA base atoms in my pdb record are
different to the one in top_heav.lib, Should I change it in my pdb or Should
I rewrite the top in order to it matches with that of pdb file. Which method
would be easier? . Below I paste a desoxi Gua from top_heav.lib (left) and a
Gua residue from my template pdb in order to show the differences (right):

RESI DGUA    -1.00000
ATOM P       P       1.50000          //    ATOM     37  P      DG A
3      49.258  12.669   8.835
ATOM OP1  ON3    -0.80000       //   ATOM     38  OP1  DG A   3      48.625
13.322   7.669
ATOM OP2  ON3    -0.80000       //   ATOM     39  OP2  DG A   3      49.792
11.303   8.659
ATOM O5'    ON2    -0.55000      //   ATOM     40  O5'   DG A   3
50.393  13.597   9.434
ATOM C5'    CN8     0.10000       //    ATOM     41  C5'  DG A   3
50.007  14.836  10.056
ATOM C4'    CN6     0.20000       //   ATOM     42  C4'  DG A   3
50.897  15.123  11.268
ATOM O4'    ON6    -0.40000      //   ATOM     43  O4'  DG A   3
50.655  14.196  12.319
ATOM C1'     CN6B    0.20000     //   ATOM     44  C3'  DG A   3
52.366  15.009  10.907
ATOM N9      NN2    -0.14000      //   ATOM     45  O3'  DG A   3
53.017  15.983  11.686
ATOM C4      CN5     0.14000       //  ATOM     46  C2'  DG A   3
52.724  13.583  11.293
ATOM N3      NN3A   -0.66000     //   ATOM     47  C1'  DG A   3
51.785  13.331  12.470
ATOM C2     CN2     0.76000       //   ATOM     48  N9   DG A   3
51.356  11.909  12.533
ATOM N1     NN2G   -0.10000     //   ATOM     49  C4   DG A   3      51.166
11.181  13.676
ATOM N2     NN1     0.00000       //   ATOM     50  C8   DG A   3
51.170  11.020  11.508
ATOM C6     CN1     0.55000       //   ATOM     51  N7   DG A   3
50.833   9.812  11.874
ATOM O6     ON1    -0.47000      //  ATOM     52  C5   DG A   3
50.777   9.903  13.268
ATOM C5   CN5    -0.08000        //   ATOM     53  C6   DG A   3
50.374   8.977  14.276
ATOM N7    NN4    -0.69000       //  ATOM     54  O6   DG A   3
49.799   7.879  14.135
ATOM C8    CN4     0.69000       //  ATOM     55  N1   DG A   3
50.574   9.420  15.560
ATOM C2'   CN6C    0.00000      //  ATOM     56  C2   DG A   3      51.068
10.663  15.839
ATOM C3'   CN6     0.10000       //  ATOM     57  N3   DG A   3      51.310
11.614  14.951
ATOM O3'   ON2    -0.55000       //  ATOM     58  N2   DG A   3      51.319
10.942  17.075

I also changed my alignment in order to the bases can be recognized:

>P1; TCP16
sequence:TCP16:::::::0.00:0.00
tjltllljjjejle
/
tjltllljjjejle
/
TPKDRHLKIGGRDRRIRI-----PPSVAPQLFRLTKELGFKTDGETVSWLLQNAEPAIFA
ATGHG
/
TPKDRHLKIGGRDRRIRI-----PPSVAPQLFRLTKELGFKTDGETVSWLLQNAEPAIFA
ATGHG
*
>P1; TCP16
structureX:TCP16:1:A:148:D:::-1.00:-1.00
tjltllljjjejle
/
tjltllljjjejle
/
TPKDRHLKIGGRD-----RRIRIPPSVAPQLFRLTKELGFKTDGETVSWLLQNAEPAIFA
ATGHG
/
TPKDRHLKIGGRD-----RRIRIPPSVAPQLFRLTKELGFKTDGETVSWLLQNAEPAIFA
ATGHG
*
Below I also paste the python script that I've used in the modelling. May be
someone can find any error o misleading command.

# Loop refinement of an existing model
from modeller import *
from modeller.automodel import *
log.verbose()
env = environ()
# directories for input atom files
env.io.atom_files_directory = ['.', '../atom_files']
#env.io.hetatm = True

# Create a new class based on 'loopmodel' so that we can redefine
# select_loop_atoms (necessary)
class MyLoop(loopmodel):

    def special_restraints(self, aln):
        rsr = self.restraints
        at = self.atoms

        rsr.add(forms.gaussian(group=physical.xy_distance,
                               feature=features.distance(at['CZ:45:C'],
                                                         at['O6:6:A']),
                               mean=3.0, stdev=0.5))

        rsr.add(forms.gaussian(group=physical.xy_distance,
                               feature=features.distance(at['CZ:105:D'],
                                                         at['O6:20:B']),
                               mean=3.0, stdev=0.5))

    # This routine picks the residues to be refined by loop modeling
    #def special_restraints(self, aln):

    def select_loop_atoms(self):
         #Two loops for refinement at the same time

     return selection(self.residue_range('44:C', '47:C'),
                         self.residue_range('103:D', '106:D'))

m = MyLoop(env,
           alnfile  = 'align2.ali' ,
           inimodel='TCP16.B99990001.pdb', # initial model of the target
           sequence='TCP16')               # code of the target


m.loop.starting_model= 1           # index of the first loop model
m.loop.ending_model  = 1           # index of the last loop model
m.loop.md_level = refine.very_slow  # loop refinement method

m.make()

Any help or advice will be very appreciated.

Sergio

-- 
Sergio Garay
Dr. en Ciencias Biol?gicas
Facultad de Bioquimica y Cs. Biol?gicas
Universidad Nacional del Litoral
Santa Fe - Argentina
C.C. 242 - Ciudad Universitaria - C.P. S3000ZAA
Argentina
Ph. +54 (342) 4575-213
Fax. +54 (342) 4575-221
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