Novel soluble expression technologies derived from unique properties of halophilic proteins

Recombinant production of mammalian cytoplasmic proteins plays a major role in developing pharmaceutical products. Here we describe two expression technologies using unique nature of halophilic bacteria. One of such properties of halophilic bacteria is accumulation of compatible solutes in the cytoplasm. As the compatible solutes enhance protein solubility and folding, one might utilize these bacteria for cytoplasmic soluble expression of recombinant proteins, as described in this review. Another uniqueness is high reversibility of thermally unfolded halophilic proteins. Here we show that one such protein, β-lactamase (BLA), is highly soluble both in the native and thermally unfolded states and reversibly refolds after thermal melting. This makes BLA as a potential fusion partner for soluble expression of target proteins. The BLA fusion technology is also introduced in the review.