[gmx-users] Get pdb2gmx not to treat the first nucleotide in a chain as 5'

[Peter Stern]

I have a chain of RNA in complex with a protein.
The pdb file is missing the first two nucleotides and starts with the third including the PO2 group.
pdb2gmx identifies this as the 5' terminal nucleotide and tries to create the topology from rna.rtp using RA5 as the "residue" type.
Thus it  doesn't like the fact that the coordinates contain a P atom and fails.  I would like to avoid removing the coordinates for PO2.
How can I get pdb2gmx to treat the first (and last in other cases) nucleotide as a "normal" residue?
Simply changing the name of the residue from A to RA does not work.

Thanks,
Peter Stern