def get_sequence(self):
"""Return the AA sequence as a Seq object.
@return: polypeptide sequence
@rtype: L{Seq}
"""
s=""
for res in self:
s += to_one_letter_code.get(res.get_resname(), 'X')
seq=Seq(s, generic_protein)
return seq
def __init__(self, model, pdb_file, dssp="dssp"):
"""
@param model: the first model of the structure
@type model: L{Model}
@param pdb_file: a PDB file
@type pdb_file: string
@param dssp: the dssp executable (ie. the argument to os.system)
@type dssp: string
"""
# create DSSP dictionary
dssp_dict, dssp_keys = dssp_dict_from_pdb_file(pdb_file, dssp)
dssp_map = {}
dssp_list = []
def resid2code(res_id):
"""Serialize a residue's resseq and icode for easy comparison."""
return '%s%s' % (res_id[1], res_id[2])
# Now create a dictionary that maps Residue objects to
# secondary structure and accessibility, and a list of
# (residue, (secondary structure, accessibility)) tuples
for key in dssp_keys:
chain_id, res_id = key
chain = model[chain_id]
try:
res = chain[res_id]
except KeyError:
# In DSSP, HET field is not considered in residue identifier.
# Thus HETATM records may cause unnecessary exceptions.
# (See 3jui chain A res 593.)
# Try the lookup again with all HETATM other than water
res_seq_icode = resid2code(res_id)
for r in chain:
if r.id[0] not in (' ', 'W'):
# Compare resseq + icode
if resid2code(r.id) == res_seq_icode:
# Found a matching residue
res = r
break
else:
raise KeyError(res_id)
# For disordered residues of point mutations, BioPython uses the
# last one as default, But DSSP takes the first one (alternative
# location is blank, A or 1). See 1h9h chain E resi 22.
# Here we select the res in which all atoms have altloc blank, A or
# 1. If no such residues are found, simply use the first one appears
# (as DSSP does).
if res.is_disordered() == 2:
for rk in res.disordered_get_id_list():
# All atoms in the disordered residue should have the same
# altloc, so it suffices to check the altloc of the first
# atom.
altloc = res.child_dict[rk].get_list()[0].get_altloc()
if altloc in tuple('A1 '):
res.disordered_select(rk)
break
else:
# Simply select the first one
res.disordered_select(res.disordered_get_id_list()[0])
# Sometimes point mutations are put into HETATM and ATOM with altloc
# 'A' and 'B'.
# See 3piu chain A residue 273:
# <Residue LLP het=H_LLP resseq=273 icode= >
# <Residue LYS het= resseq=273 icode= >
# DSSP uses the HETATM LLP as it has altloc 'A'
# We check the altloc code here.
elif res.is_disordered() == 1:
# Check altloc of all atoms in the DisorderedResidue. If it
# contains blank, A or 1, then use it. Otherwise, look for HET
# residues of the same seq+icode. If not such HET residues are
# found, just accept the current one.
altlocs = set(a.get_altloc() for a in res.get_unpacked_list())
if altlocs.isdisjoint('A1 '):
# Try again with all HETATM other than water
res_seq_icode = resid2code(res_id)
for r in chain:
if r.id[0] not in (' ', 'W'):
if resid2code(r.id) == res_seq_icode and \
r.get_list()[0].get_altloc() in tuple('A1 '):
res = r
break
aa, ss, acc, phi, psi = dssp_dict[key]
res.xtra["SS_DSSP"] = ss
res.xtra["EXP_DSSP_ASA"] = acc
res.xtra["PHI_DSSP"] = phi
res.xtra["PSI_DSSP"] = psi
# Relative accessibility
resname = res.get_resname()
try:
rel_acc = acc/MAX_ACC[resname]
except KeyError:
# Invalid value for resname
rel_acc = 'NA'
else:
if rel_acc > 1.0:
rel_acc = 1.0
res.xtra["EXP_DSSP_RASA"] = rel_acc
# Verify if AA in DSSP == AA in Structure
# Something went wrong if this is not true!
# NB: DSSP uses X often
resname = to_one_letter_code.get(resname, 'X')
if resname == "C":
# DSSP renames C in C-bridges to a,b,c,d,...
# - we rename it back to 'C'
if _dssp_cys.match(aa):
aa = 'C'
# Take care of HETATM again
if (resname != aa) and (res.id[0] == ' ' or aa != 'X'):
raise PDBException("Structure/DSSP mismatch at %s" % res)
dssp_map[key] = ((res, ss, acc, rel_acc, phi, psi))
dssp_list.append((res, ss, acc, rel_acc, phi, psi))
AbstractResiduePropertyMap.__init__(self, dssp_map, dssp_keys,
dssp_list)
def __init__(self, model, pdb_file, dssp="dssp"):
"""
@param model: the first model of the structure
@type model: L{Model}
@param pdb_file: a PDB file
@type pdb_file: string
@param dssp: the dssp executable (ie. the argument to os.system)
@type dssp: string
"""
# create DSSP dictionary
dssp_dict, dssp_keys = dssp_dict_from_pdb_file(pdb_file, dssp)
dssp_map = {}
dssp_list = []
def resid2code(res_id):
"""Serialize a residue's resseq and icode for easy comparison."""
return '%s%s' % (res_id[1], res_id[2])
# Now create a dictionary that maps Residue objects to
# secondary structure and accessibility, and a list of
# (residue, (secondary structure, accessibility)) tuples
for key in dssp_keys:
chain_id, res_id = key
chain = model[chain_id]
try:
res = chain[res_id]
except KeyError:
# In DSSP, HET field is not considered in residue identifier.
# Thus HETATM records may cause unnecessary exceptions.
# (See 3jui chain A res 593.)
# Try the lookup again with all HETATM other than water
res_seq_icode = resid2code(res_id)
for r in chain:
if r.id[0] not in (' ', 'W'):
# Compare resseq + icode
if resid2code(r.id) == res_seq_icode:
# Found a matching residue
res = r
break
else:
raise KeyError(res_id)
# For disordered residues of point mutations, BioPython uses the
# last one as default, But DSSP takes the first one (alternative
# location is blank, A or 1). See 1h9h chain E resi 22.
# Here we select the res in which all atoms have altloc blank, A or
# 1. If no such residues are found, simply use the first one appears
# (as DSSP does).
if res.is_disordered() == 2:
for rk in res.disordered_get_id_list():
# All atoms in the disordered residue should have the same
# altloc, so it suffices to check the altloc of the first
# atom.
altloc = res.child_dict[rk].get_list()[0].get_altloc()
if altloc in tuple('A1 '):
res.disordered_select(rk)
break
else:
# Simply select the first one
res.disordered_select(res.disordered_get_id_list()[0])
# Sometimes point mutations are put into HETATM and ATOM with altloc
# 'A' and 'B'.
# See 3piu chain A residue 273:
# <Residue LLP het=H_LLP resseq=273 icode= >
# <Residue LYS het= resseq=273 icode= >
# DSSP uses the HETATM LLP as it has altloc 'A'
# We check the altloc code here.
elif res.is_disordered() == 1:
# Check altloc of all atoms in the DisorderedResidue. If it
# contains blank, A or 1, then use it. Otherwise, look for HET
# residues of the same seq+icode. If not such HET residues are
# found, just accept the current one.
altlocs = set(a.get_altloc() for a in res.get_unpacked_list())
if altlocs.isdisjoint('A1 '):
# Try again with all HETATM other than water
res_seq_icode = resid2code(res_id)
for r in chain:
if r.id[0] not in (' ', 'W'):
if resid2code(r.id) == res_seq_icode and \
r.get_list()[0].get_altloc() in tuple('A1 '):
res = r
break
aa, ss, acc, phi, psi = dssp_dict[key]
res.xtra["SS_DSSP"] = ss
res.xtra["EXP_DSSP_ASA"] = acc
res.xtra["PHI_DSSP"] = phi
res.xtra["PSI_DSSP"] = psi
# Relative accessibility
resname = res.get_resname()
try:
rel_acc = acc / MAX_ACC[resname]
except KeyError:
# Invalid value for resname
rel_acc = 'NA'
else:
if rel_acc > 1.0:
rel_acc = 1.0
res.xtra["EXP_DSSP_RASA"] = rel_acc
# Verify if AA in DSSP == AA in Structure
# Something went wrong if this is not true!
# NB: DSSP uses X often
resname = to_one_letter_code.get(resname, 'X')
if resname == "C":
# DSSP renames C in C-bridges to a,b,c,d,...
# - we rename it back to 'C'
if _dssp_cys.match(aa):
aa = 'C'
# Take care of HETATM again
if (resname != aa) and (res.id[0] == ' ' or aa != 'X'):
raise PDBException("Structure/DSSP mismatch at %s" % res)
dssp_map[key] = ((res, ss, acc, rel_acc, phi, psi))
dssp_list.append((res, ss, acc, rel_acc, phi, psi))
AbstractResiduePropertyMap.__init__(self, dssp_map, dssp_keys,
dssp_list)
