[gmx-users] TP2 problem

[farial tavakoli]

Dear GMX users
I need to generate a topology for my complex (protein + peptide) using CHARMM36 ff in gromacs , since It has 2 phosphotyrosine residues. I did these steps:
at first , I converted TYR in pdb file to TP2, accordingly the merged.tpr file of CHARMM36 ff.
then , changed P atom in pdb file to P1 and changed O1P,O2P,O3P in pdb file to O2,O3,O4 , respectively, in accord with merged.tpr file
 added TP2 residue to residuetype.dat file as a protein in working directory
My protein has 323 residues , start terminus: GLY 1  and  end terminus : ILE 323My peptide has 7 residues , start terminus : THR 1  and  end terminus :  PRO 7
but when issued this command:
 gmx pdb2gmx -f .pdb -o .gro -ignh -water tip4p 
 faced to this error and warnings:
Start terminus GLY-1: GLY-NH3+
End terminus ILE-323: COO-
Opening force field file ./charmm36-jul2017.ff/merged.arn
Checking for duplicate atoms....
Generating any missing hydrogen atoms and/or adding termini.
Now there are 323 residues with 5204 atoms
Chain time...

Back Off! I just backed up topol_Protein_chain_A.itp to ./#topol_Protein_chain_A.itp.14#
Making bonds...
Number of bonds was 5261, now 5261
Generating angles, dihedrals and pairs...
Before cleaning: 13845 pairs
Before cleaning: 14000 dihedrals
Keeping all generated dihedrals
Making cmap torsions...
There are  321 cmap torsion pairs
There are 14000 dihedrals,  863 impropers, 9560 angles
          13764 pairs,     5261 bonds and     0 virtual sites
Total mass 36882.800 a.m.u.
Total charge -7.000 e
Writing topology

Back Off! I just backed up posre_Protein_chain_A.itp to ./#posre_Protein_chain_A.itp.14#
Processing chain 2 'B' (73 atoms, 7 residues)
Analysing hydrogen-bonding network for automated assignment of histidine
 protonation. 12 donors and 10 acceptors were found.
There are 11 hydrogen bonds
Will use HISE for residue 2
Identified residue THR1 as a starting terminus.
Warning: Residue TP23 in chain has different type (Other) from starting residue THR1 (Protein).
Warning: Residue TP24 in chain has different type (Other) from starting residue THR1 (Protein).
Warning: Residue LEU5 in chain has different type (Protein) from starting residue THR1 (Protein).
Warning: Residue LEU6 in chain has different type (Protein) from starting residue THR1 (Protein).
Warning: Residue PRO7 in chain has different type (Protein) from starting residue THR1 (Protein).
Identified residue HIS2 as a ending terminus.
8 out of 8 lines of specbond.dat converted successfully
Start terminus THR-1: NH3+
End terminus HIS-2: COO-
Opening force field file ./charmm36-jul2017.ff/merged.arn

-------------------------------------------------------
Program:     gmx pdb2gmx, version 2016.4
Source file: src/gromacs/gmxpreprocess/pdb2gmx.cpp (line 753)

Fatal error:
Atom OXT in residue PRO 7 was not found in rtp entry PRO with 14 atoms
while sorting atoms.
.

For more information and tips for troubleshooting, please check the GROMACSwebsite at http://www.gromacs.org/Documentation/Errors
I am confused and dont understand where the problem is? It has taken my time for 2 days. I would really appreciate it if anybody helps me to solve this problem. 
best regardsFarial