The role of yeast extract in the expression of intrinsically disordered proteins in Escherichia coli

The protein structure-function paradigm in which proteins can function only if it exists with a well-defined 3-D structure is often disputed with the occurrence of Intrinsically disordered proteins (IDPs) . These proteins although lacking in defined,  ordered structures play crucial roles in biological processes. E.coli , a widely used protein expression system was used to express the Hox protein, Ultrabithorax (Ubx) however the intrinsically disordered regions of this protein renders them susceptible to proteolysis and aggregation. The yeast extract component of the LB Miller Broth used to cultivate E.coli was found to have a significant impact on the resulting expressed protein. Although high biomass concentrations were produced when TASTONE 154 was used, the issue of proteolysis was observed . AMBERFERM 5902 on the other hand was found to be the better yeast extract substitute when expressing Ubx in E.coli as it led to greater protein expression, lower proteolysis and thus a higher yield of desired soluble full length Ubx monomer.