Biochemical and structural characterizations of a protein are the prerequisite for the further understanding of its biological role and potential applications. The expression of recombinant protein is almost unavoidable to produce the amount of the protein required for these studies, especially at the industrial level. Escherichia coli is the single most used system for recombinant protein expression and the first choice for a trial expression. Besides the inherited defects of its prokaryotic origin, the E. coli system has problems like low protein solubility and formation of inclusion bodies. To improve the solubility while assisting correct folding of the target protein, fusing a tag protein prior to its N-terminus is one of the common approaches. GST, MBP, Trx and SUMO proteins are among the most used tags by providing different advantages during recombinant protein expression. Msyb, a small and acidic protein native to E. coli, is another example that could improve the solubility of the target protein. While the biophysical and biochemical properties of these common tag proteins have been studied to a great extent, Msyb protein remains largely uncharacterized. Here, using solution-state NMR, our near-complete resonance assignment of Msyb provides a basis for future structure determination which would help to expand its usage as a common tag protein.
Keywords: Acidic; E. coli; Fusion; Msyb; Protein solubility tag; SUMO.