In addition to everything Mark said, also realize that there may be a fundamental problem in everything you are doing: there are missing atoms in the original 1K4C structure. If you have not modeled them back in, the appropriate CG particles will not necessarily all be placed in your CG structure, but the topology will be written such that it expects all the correct atoms to be there.

At first glance, Arg117 is going to cause headaches - it is missing all atoms beyond CB, and since CG and NE are necessary for MARTINI's definition of an ARG residue, you can bet this will be a problem.

-Justin

Mark Abraham wrote:
sunny mishra wrote:
Hi Justin,

Thanks for the reply and here is the following which I am doing. I would
appreciate if you can point out my errors.


1) I am working on 1K4C (KcSA) and i downloaded that from www.pdb.org and
after that I cleaned the PBD file, removed all the HETATOMS and ATOMS with
ligand A & B and also removed the TER atoms. So my cleaned PDB file i.e.
(1K4C_clean.pdb) consists of atoms with ligands C and #of atoms are 765.

2) After getting the 1K4C_clean.pdb I converted the atomic structure to CG
structure using awk script...something like this

awk -f atom2cg.awk 1K4C_clean.pdb > 1K4C_cleanCG.pdb

Here you create 1K4C_cleanCG.pdb

3) Then I got the sequence of 1K4C_clean.pdb using vmd and saved that as
1K4C_clean.txt and with the help of the following command I got the .seq
file...

But below you create your .itp starting from "1K4C_clean", which at least means you haven't copied your correct grep line, and might indicate the mismatch between your structure and topology.

grep -A 1 1K4C_clean 1K4C_clean.txt > 1K4C_clean.seq

4) Then using dssp I got the .ssd file for 1K4C_clean.pdb....

dsspcmbi 1K4C_clean.pdb 1K4C_clean.dssp
dssp2ssd.py 1K4C_clean.dssp -o 1K4C_clean.ssd

5) After preparing the secondary structure files I generated the MARTINI
topology files like this :

seq2itp.pl 1K4C_clean.seq 1K4C_clean.ssd > 1K4C_clean.itp

6) The next step is to make the topology file and I made like this.....

; Include Martini Topology
#include "martini_v2.1.itp"

; Include protein topology
#include "1K4C_clean.itp"


[ system ]
; Name
Membrane Protein

[ molecules ]
; compound       #mols
Protein            1

7) Then I made the .gro file using genbox.....

genbox -cp 1K4C_cleanCG.pdb -box 10 10 10 -o 1K4C_cleanCG.gro

(In the previous email as you said that I need to make the .gro file of CG
structure of protein so I used 1K4C_cleanCG.pdb)

A .gro file is almost never essential. A structure file with a suitable periodic box can be.

8) Now I want to minimize the system.....

grompp -f em.mdp -c 1K4C_cleanCG.gro -p 1K4C_clean.top -maxwarn 10

and then error comes...........

:-)  G  R  O  M  A  C  S
(-:

                   GROningen MAchine for Chemical Simulation

                            :-)  VERSION 4.0.5  (-:


Written by David van der Spoel, Erik Lindahl, Berk Hess, and others.
       Copyright (c) 1991-2000, University of Groningen, The Netherlands.
             Copyright (c) 2001-2008, The GROMACS development team,
            check out http://www.gromacs.org for more information.

         This program is free software; you can redistribute it and/or
          modify it under the terms of the GNU General Public License
         as published by the Free Software Foundation; either version 2
             of the License, or (at your option) any later version.

                                :-)  grompp  (-:

Option     Filename  Type         Description
------------------------------------------------------------
  -f         em.mdp  Input, Opt!  grompp input file with MD parameters
 -po      mdout.mdp  Output       grompp input file with MD parameters
-c 1K4C_cleanCG.pdb Input Structure file: gro g96 pdb tpr tpb tpa
  -r       conf.gro  Input, Opt.  Structure file: gro g96 pdb tpr tpb tpa
 -rb       conf.gro  Input, Opt.  Structure file: gro g96 pdb tpr tpb tpa
  -n      index.ndx  Input, Opt.  Index file
  -p 1K4C_clean.top  Input        Topology file
 -pp  processed.top  Output, Opt. Topology file
  -o      topol.tpr  Output       Run input file: tpr tpb tpa
  -t       traj.trr  Input, Opt.  Full precision trajectory: trr trj cpt
  -e       ener.edr  Input, Opt.  Energy file: edr ene

Option       Type   Value   Description
------------------------------------------------------
-[no]h       bool   no      Print help info and quit
-nice        int    0       Set the nicelevel
-[no]v       bool   yes     Be loud and noisy
-time        real   -1      Take frame at or first after this time.
-[no]rmvsbds bool yes Remove constant bonded interactions with virtual
                            sites
-maxwarn     int    10      Number of allowed warnings during input
processing
-[no]zero    bool   no      Set parameters for bonded interactions
without
                            defaults to zero instead of generating an
error
-[no]renum   bool   yes     Renumber atomtypes and minimize number
of

atomtypes

Ignoring obsolete mdp entry 'title'
Ignoring obsolete mdp entry 'cpp'
Replacing old mdp entry 'unconstrained_start' by 'continuation'

Back Off! I just backed up mdout.mdp to ./#mdout.mdp.8#
checking input for internal consistency...

NOTE 1 [file em.mdp, line unknown]:
For energy conservation with switch/shift potentials, rlist should be 0.1
  to 0.3 nm larger than rcoulomb.


NOTE 2 [file em.mdp, line unknown]:
For energy conservation with switch/shift potentials, rlist should be 0.1
  to 0.3 nm larger than rvdw.

processing topology...
Generated 0 of the 465 non-bonded parameter combinations
Excluding 1 bonded neighbours molecule type 'Protein'

NOTE 3 [file 1K4C_clean.top, line 15]:
  System has non-zero total charge: 2.000000e+00



processing coordinates...

-------------------------------------------------------
Program grompp, VERSION 4.0.5
Source code file: grompp.c, line: 362

Fatal error:
number of coordinates in coordinate file (1K4C_cleanCG.pdb, 209)
             does not match topology (1K4C_clean.top, 216)
-------------------------------------------------------

I don't know where I have done the mistake...your help will be highly
appreciable in this case.

Here you've got a 7-atom difference, and...

           -------------------------------------------------------
           Program grompp, VERSION 4.0.5
           Source code file: grompp.c, line: 362

           Fatal error:
           number of coordinates in coordinate file (1K4C_cg.gro, 1127)
                       does not match topology (1K4C.top, 1166)
           -------------------------------------------------------

...here you're different by 39 atoms. That indicates a procedure that differed by more than just not adding solvent.

With a complex multi-step system preparation, you are much better served by writing the steps down in a shell script so that you really do things the same way every time. Science is still science, even on a computer, and your work must be reproducible. Moreover, then when you ask for help, you're not presenting contradictions and non sequiturs that frustrate attempts to help you :-)

In any case, my earlier advice still applies - it should be a matter of 10 minutes work to compare your clean .itp and .gro to see what atoms are causing the problem. Then, work backwards.

Mark
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--
========================================

Justin A. Lemkul
Ph.D. Candidate
ICTAS Doctoral Scholar
Department of Biochemistry
Virginia Tech
Blacksburg, VA
jalemkul[at]vt.edu | (540) 231-9080
http://www.bevanlab.biochem.vt.edu/Pages/Personal/justin

========================================
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