Protein Stabilization by Insertion Into a Thermophilic Protein

Protein stability is a fundamental problem that may restrict biotechnology applications of proteins. We have previously reported that one can improve stability of proteins by insertion into a thermophilic maltodextrin binding protein from Pyrococcus furiosus (PfMBP). Our method employs no changes in the primary sequence of target proteins and shows a high potential to increase stability of proteins without compromise in their intrinsic properties, such as soluble expression levels and enzyme activities. In insertional fusion, the N- and C-termini of the target protein domain are tethered to the internal segments of PfMBP, possibly reducing the conformational flexibility of these termini. Depending on the insertion sites, insertional fusion also permits distinct structural arrangements between the host and guest protein domains and thus could differentiate inter-domain interactions. We will report our recent progress in the mechanism by which an inserted protein becomes stabilized by insertional fusion into PfMBP.