Production of secreted, soluble human two-domain CD4 protein in Escherichia coli

The two-domain form of recombinant soluble human CD4 (rsCD4(183)) has been used for structural studies and to probe the interaction of CD4 with its li gands. rsCD4(183) has generally been produced in Escherichia coli in the fo rm of inclusion bodies. The generation of conformationally native protein f rom these inclusion bodies is a time-consuming and inefficient process, req uiring a refolding step. Here, we describe a procedure for producing 2-4 mg of secreted, conformationally native rsCD4(183) per liter of E. coli, comp letely bypassing the requirement for protein refolding in vitro. Furthermor e, the yield of active protein is comparable to that reported for expressio n systems that generate inclusion bodies. (C) 1999 Elsevier Science B.V. Al l rights reserved.