An efficient thermostabilization strategy based on self-assembling amphipathic peptides for fusion tags

Self-assembling amphipathic peptides (SAPs) have been used as stabilization tags to improve enzyme stability but do not function uniformly well with all target enzymes. Here, the key factors involved in SAPs stabilization were identified as the SAP length and linker length and flexibility, using S1 (AEAEAKAK)₂ as an originated SAP and polygalacturonate lyase (PGL) as model protein. Biochemical analysis demonstrated that SAPs could induce loose protein oligomerization via intermolecular hydrophobic interactions. Based on this mechanism, a comprehensive protein stabilization strategy was proposed, in which a library of stabilizing tags through random combination of different SAPs and linker peptides was developed to design the fusion composition while the sodium chloride (NaCl) was used to enhance the intermolecular hydrophobic interactions. By using the strategy, the PGL, lipoxygenase (LOX) and L-asparaginase exhibited 33.25-, 17.55- and 15.6-fold increases, respectively, in the t_1/2 value relative to that of the corresponding wild-type enzyme. The SAP library therefore shows great application potential in stability enhancement of enzymes/proteins.