Other methods can be employed to potentially suppress heterologous protein toxicity. In one example, a target protein can be expressed as a fusion protein. Common options include constructing a fusion between the target protein and maltose binding protein (pMAL™ protein fusion and purification system, NEB #E8200) or an intein tag (IMPACT™ Kit, NEB #E6901). In severe cases of target protein toxicity, the IMPACT Kit may be used to express and purify a non-toxic fragment of the target to which a protein or peptide can be ligated, via intein-mediated protein ligation (IPL), to produce the complete native protein. Additionally, proteins toxic to one host may be better tolerated in a different host strain or another type of organism. Accordingly, NEB offers multiple E.coli expression strains and a K. lactis yeast expression system (NEB #E1000). Finally, if cellular toxicity is unavoidable, cell-free protein expression may be achieved using the PURExpress® in vitro protein synthesis kit (NEB #E6800).