I want to force a non-proline peptide bond to the cis
configuration in a 64-residue model.
I found a routine to force Pro residue to the cis configuration
in the FAQ.
I assumed that it would not make a difference if the residue it
applies to is not an actual proline
and I include the routine in my .py script, but I got only models
with the trans peptide configuration.
This is an example of my .py file :
# Homology modelling by the automodel class
from modeller import * # Load standard Modeller classes
from modeller.automodel import * # Load the
automodel class
# Redefine the special_patches routine to include the additional
disulfides
# (this routine is empty by default):
class mymodel(automodel): def
special_patches(self, aln): # A disulfide between residues 12 and 63: self.patch(residue_type='DISU',
residues=(self.residues['12'], self.residues['63']))
# A
disulfide between residues 16 and 36: self.patch(residue_type='DISU',
residues=(self.residues['16'], self.residues['36']))
# A
disulfide between residues 22 and 46: self.patch(residue_type='DISU',
residues=(self.residues['22'], self.residues['46']))
# A
disulfide between residues 26 and 48: self.patch(residue_type='DISU',
residues=(self.residues['26'], self.residues['48']))
# Redefine the special_restraints routine to force Pro to cis
conformation:
# (this routine is empty by default):
class mymodel(automodel): def special_restraints(self, aln): a =
self.atoms cispeptide(self.restraints, atom_ids1=(a['O:9'], a['C:9'], a['N:10'], a['CA:10']), atom_ids2=(a['CA:9'], a['C:9'], a['N:10'], a['CA:10']))
log.verbose() # request verbose output
env = environ() # create a new MODELLER environment to build
this model in
# directories for input atom files
env.io.atom_files_directory = ['./']
a = automodel(env,
alnfile =
'AahII-cis.ali', # alignment filename
knowns =
'1PTX', # codes of the templates
sequence =
'AahII-cis') # code of
the target
a.starting_model=
1 # index of the first model
a.ending_model =
1 # index of the last model
# (determines how many models to calculate)
I noticed only 3 lines in the log file with warnings:
...
getf_______W> RTF restraint not found in the atoms
list:
residue type, indices:
7 64
atom
names :
C +N
atom
indices :
503 0
getf_______W> RTF restraint not found in the atoms list:
residue type, indices:
7 64
atom
names :
C CA +N
O
atom
indices :
503 496 0 504
...
mdtrsr__446W> A potential that relies on one protein is
used, yet you have at
least one known structure available. MDT, not
library, potential is used.