clean_pdb_keep_ligand.py

Go to the documentation of this file.

#!/usr/bin/python
## Written and improved over the years by Phil, Rhiju, Olli and Mike
## Lucas Nivon, Nov 2010, modifying to keep HETATMS which are not non-canonical ligands
## Usage: python clean_pdb_keep_ligand.py 1dqb -ignorechain
## Note that the database for the original pdbs is at local_pdb_database, change this as needed at top of script
###############################################################

import string
from sys import argv,stderr
from os import popen,system
from os.path import exists,basename
from amino_acids import longer_names
from amino_acids import modres

##############################  set your scaffold source here #################################
local_pdb_database = "/lab/shared/scaffolds/"
keep_ligand = True    # set to false to throw away all HETATMs, not just the confusing non-canonical Amino Acids
###############################################################################################

shit_stat_insres      = False
shit_stat_altpos      = False
shit_stat_modres      = False
shit_stat_misdns     = False

hetatm_list = []     ### keep a record of the hetatms observed so far that are not in the amino acid dictionary

CA_MODEL = True
NO_OCCUPANCY = True

fastaseq = ""
pdbfile = ""
def check_and_print_pdb( count, residue_buffer, residue_letter ):
  global fastaseq
  global pdbfile
  global CA_MODEL
  global NO_OCCUPANCY 

  ## Check that CA, N and C are present!def check_and_print_pdb( outid, residue_buffer )
  hasCA = False
  hasN = False
  hasC = False
  IsGoodLigand = False

  for line in residue_buffer:
    atomname = line[12:16]
    #Only add bb atoms if they have occupancy!
    occupancy=float(line[55:60])
    
    if occupancy > 0.0 : 
      NO_OCCUPANCY = False
    if atomname == " CA " and occupancy > 0.0: hasCA = True
    if atomname == " N  " and occupancy > 0.0:  hasN = True
    if atomname == " C  " and occupancy > 0.0:  hasC = True
    if (line[0:6] == 'HETATM' and keep_ligand): 
      IsGoodLigand = True
      
  ## if all three backbone atoms are present withoccupancy proceed to print the residue
  if hasN or hasC : CA_MODEL = False
  if ((hasCA and hasN and hasC) or (IsGoodLigand)) :
    for line in residue_buffer:
      ## add linear residue count
      newnum = '%4d ' % count
      line_edit = line[0:22] + newnum + line[27:]
      ## write the residue line
      pdbfile = pdbfile + line_edit

    ## finally print residue letter into fasta stream
    fastaseq = fastaseq + residue_letter

    ## count up residue number
    count = count + 1
    return True

  return False


assert( len(argv)>2)
pdbname = argv[1]
pdbcode = argv[1]
chainid = argv[2]

if (pdbname[-4:] != '.pdb' and pdbname[-8:] != '.pdb1.gz'):
    pdbname += '.pdb'

outfile = pdbname

nopdbout = 0
if argv.count('-nopdbout'):
    nopdbout = 1

removechain = 0
if argv.count('-nochain'):
    removechain = 1

ignorechain = 0
if argv.count('-ignorechain'):
    ignorechain = 1

netpdbname = local_pdb_database + pdbname[1:3] + '/' + pdbname[0:4] + '/' + argv[1] + '_0.pdb'
#print "getting the name right:", netpdbname
if not exists(netpdbname):
    netpdbname = pdbname


if netpdbname[-3:]=='.gz':
    lines = popen( 'zcat '+netpdbname,'r').readlines()
else:
    lines = open(netpdbname,'r').readlines()


oldresnum = '   '
count = 1;
modifiedres = ''


residue_buffer = []
residue_letter = ''
residue_invalid = False

if chainid == '_':
    chainid = ' '

for i in range(len(lines)):
    line = lines[i]

    if len(line)>5 and line[:6]=='ENDMDL':break #Its an NMR model.

    if (chainid == line[21] or ignorechain):
        line_edit = line
        if line[0:3] == 'TER':
            continue
        elif (line[0:6] == 'HETATM'):
            ok = False
            #print "found a HETATM", line_edit

            ## Is it a modified residue ?
            if modres.has_key( line[17:20] ):
              ## if so replace it with its canonical equivalent !
                line_edit = 'ATOM  '+line[6:17]+modres[line[17:20]] +line[20:]
                modifiedres = modifiedres +  line[17:20]  + ',  '
                ## dont count MSEs as modiied residues (cos they're so common and get_pdb deal with them previosuly)
                if line[17:20] != "MSE":
                  shit_stat_modres = True
                ok = True

            ## other substitution (of atoms mainly)
            elif (line[17:20]=='MSE'): #Selenomethionine
                if (line_edit[12:14] == 'SE'):
                    line_edit = line_edit[0:12]+' S'+line_edit[14:]
                if len(line_edit)>75:
                    if (line_edit[76:78] == 'SE'):
                        line_edit = line_edit[0:76]+' S'+line_edit[78:]
            else:
              line_edit = line
#              print "found a HETATM", line
              if line[17:20] != "MSE":
                shit_stat_modres = True
              hetatm_list.append(line[17:20])
              ok = True

            if not ok:
              continue # skip this atom if we havnt found a conversion

        if (line_edit[0:4] == 'ATOM') or (line_edit[0:6] == 'HETATM' ):
##            if line_edit[13:14]=='P': #Nucleic acid? Skip.
##                resnum = line_edit[23:26]
##                oldresnum = resnum
##                while (resnum == oldresnum):
##                    print "HERE"
##                    i += 1
##                    line = lines[i]
##                    resnum = line_edit[23:26]

            resnum = line_edit[22:27]

            insres = line[26]
            if insres != ' ': shit_stat_insres = True

            altpos = line[16]
            if altpos != ' ': shit_stat_altpos = True
            ## Print out the residue when the new line is for a new residue
            if not resnum == oldresnum:
                if residue_buffer != []:  ## is there a residue in the buffer ? If so print it out, then reinitialize
                  if not residue_invalid:
                    ##print "call from the loop:\n"  ## new
                    if not check_and_print_pdb( count, residue_buffer, residue_letter ):
                      ## if unsuccessful
                      shit_stat_misdns = True
                    else:
                      count = count + 1

                residue_buffer = []
                residue_letter = ''
                residue_invalid = False

                longname = line_edit[17:20]
                if longer_names.has_key(longname):
                    residue_letter = longer_names[longname];
                else:
                    residue_letter = 'X'
                    ######### residue_invalid = True

            oldresnum = resnum

            ## What does this do ?
            if line_edit[16:17] == 'A':
                line_edit = line_edit[:16]+' '+line_edit[17:]

            if line_edit[16:17] != ' ':
                continue

            if removechain:
                line_edit = line_edit[0:21]+' '+line_edit[22:]

            #print "about to append to residue_buffer####", line_edit
            residue_buffer.append( line_edit )

            #outid.write(line_edit)


#print "calling after the loop\n" ## new
if not check_and_print_pdb( count, residue_buffer, residue_letter ):
  ## if unsuccessful
  shit_stat_misdns = True
else:
  count = count + 1


flag_altpos = "---"
if shit_stat_altpos : flag_altpos = "ALT"
flag_insres = "---"
if shit_stat_insres : flag_insres = "INS"
flag_modres = "---"
if shit_stat_modres : flag_modres = "MOD"
flag_misdns = "---"
if shit_stat_misdns : flag_misdns = "DNS"

nres = len(fastaseq)
flag_successful = "OK"
if nres <= 0: 
  flag_successful = "BAD"
  if CA_MODEL: flag_successful = flag_successful + " (CA only model )"
  if NO_OCCUPANCY: flag_successful = flag_successful + " (No occupancy )"

print netpdbname, pdbname, chainid, "%5d"%nres, flag_altpos,  flag_insres,  flag_modres,  flag_misdns, flag_successful

#for item in hetatm_list:
#  print item

if chainid == ' ':  chainid = '_'
print "chainid is", chainid
if chainid == "-ignorechain":  chainid = '_00'
if nres > 0:
  if( nopdbout == 0 ):
    outfile = pdbcode + chainid + ".pdb"
    outfile = outfile.replace('.pdb1.gz','.pdb')
    outid = open( outfile, 'w')
    outid.write(pdbfile)
    outid.write("TER\n")
    outid.close()
  
  fastaid = stderr
  fastaid.write('>'+pdbname[0:4]+chainid+'\n');
  fastaid.write( fastaseq )
  fastaid.write('\n')
  fastaid.close()