EXPRESSION OF HUMAN INTERLEUKIN-11 CDNA IN ESCHERICHIA-COLI

A 551-bp hIL-11 gene fragment that includes no nucleotide sequences en coding signal polypeptide and the initial 8 amino acids of the mature protein was cloned into a high-level expression vector pEx31B of E. co li. The authors identified the recombinant plasmid. designated pEx31-I L11, by restriction endonucleases digestion and DNA sequencing. The re sulting recombinant plasmids were then used to transform E, coli strai n HB101, and expression in the PL promoter system, which is temperatur e-regulated was achieved. The expressed fusion protein amounts to 50% of total bacterial proteins. The hIL-11 protein expressed in E. coli w as fused to the N-terminal 99 amino acids of the MS2 polymerase to for m the inclusion body. These recombinant proteins on be purified to abo ut 80% by extracting inclusion body with urea. One IL-6-dependent cell line 7 TD1 was used for bioassay. The recombinant hIL-11 protein was preliminarily purified and renatured to a specific activity of 10(5) U /mg, even in the presence of an excess of a neutralizing anti-IL-6 ant ibody.