I am a bit confused about the utility of auto_overhang=true usage in
salign_multiple_struc.py for MSA computation. Even if i don't use
this line, result comes the same as _fit files are generated.
auto_overhang is designed to handle the case where the two sequences
being aligned are of very different lengths, for example trying to align
a single chain with a multi-chain protein. A regular global alignment
will try to "stretch" the shorter sequence so that its termini will
align with those of the longer sequence; auto_overhang reduces the
global alignment penalty so that the termini need not align.