PRODUCTION OF SOLUBLE AND ACTIVE RECOMBINANT MURINE INTERLEUKIN-2 IN ESCHERICHIA-COLI - HIGH-LEVEL EXPRESSION, KIL-INDUCED RELEASE, AND PURIFICATION

We describe the production of soluble murine interleukin-2 (mIL2) and its purification following regulated release in the growth medium of E scherichia coli. The system is based on the ability of the Kil protein of pMB9 to release periplasmic proteins into the growth medium. As th e kil gene is under control of the strong, but well regulatable pL pro moter, the kil bearing plasmid is stably maintained in the cell. mIL2, fused to the outer membrane protein A (OmpA) signal peptide, was secr eted into the periplasm and subsequently released into the growth medi um after induction of the kil gene. This strategy allows a quick and e asy purification of the heterologous protein without using strong dena turants or detergents, yielding a native protein with a specific biolo gical activity equal to the natural mIL2, The system permits the produ ction of mIL2 at levels up to 16 mg/liter. From a 12-liter fermentatio n, a final yield of about 30 mg of pure mIL2 was obtained. (C) 1995 Ac ademic Press, Inc.