Novel modified beta-interferons: gene cloning, expression, and biological activity in bacterial extracts.

A series of novel, modified interferons based on the structure of human beta-interferon have been expressed in Escherichia coli. Modified interferon genes were constructed from sequences derived from the natural beta-interferon gene, a synthetic beta-interferon gene, or a specific combination of the two. A total of 23 out of the 25 novel interferons exhibited antiviral (AV) and antiproliferative (AP) activity which varied from 3 to 230% and 8 to 490% of the values for beta-interferon, respectively. None of the novel interferons had only AV or AP activity, although one had a much reduced ratio of AV/AP activity compared with beta-interferon. Substitution of beta-interferon amino acids 2-7 or 28-46 resulted in interferons with significantly increased AP activity on Daudi lymphoblastoid cells (four- to fivefold). All the novel interferons except two with modifications in the 82-105 region reacted with a neutralizing beta-interferon monoclonal antibody.

Chemical synthesis and cloning of a poly(arginine)-coding gene fragment designed to aid polypeptide purification.

A 43-bp DNA duplex coding for poly(arginine) [poly(arg)] has been synthesised by modified phosphotriester procedures. It has been inserted into the Bg/II and BamHI restriction sites of a cloned synthetic beta-urogastrone (Uro) gene, under the control of the trp promoter. Subsequent induction with 3 beta-indole acrylic acid produces beta-Uro with a C-terminal poly(arg) fusion. The raised isoelectric point of this polypeptide fusion facilitates rapid purification by cation exchange chromatography. The C-terminal poly(arg) tail can be readily removed by treatment with carboxypeptidase B.