An intriguing finding came to light after further bioinformatics
investigation into the fusion site. Sequence alignment of the two
microalgal component proteins against their chosen templates revealed
that there is an insert of 64 amino acids at the fusion site. More specifically,
there are 21 amino acids prior to and 43 amino acids posterior to
the fusion site. Due to the lack of coordinates for that insert from the
template structures, the 64 amino acid sequence was blasted against
the full PDB database. Strikingly, the structure of a protein fragment
from the marine bacterium Thermotoga maritima was identified for
the 43 residue fragment right after the fusion site. In particular, the insert
appeared at chain A of the crystal structure of a trigger factor chaperone
with promiscuous substrate recognition in folding and assembly
from the T. maritima bacterium (RCSB entry: 3GU0