S99t c-11 truncated polynucleotides encoding interferon gamma polypeptide variants

Abstract

When interferon gamma (IFNG) is produced in mammalian cell lines a heterogenous population of IFNG polypeptides is obtained due to C-terminal processing of the IFNG polypeptide. Clearly, this constitutes a severe problem in that valuable polypeptide material is lost and, further, it is necessary to carry out time-consuming and cumbersome purification in order to obtain a homogenous population of active IFNG polypeptides having the desired length. It has now been found that an IFNG fragment containing 132 amino acid residues (truncated at the nucleotide level by introducing a stop-codon after the codon encoding amino acid residue no. 132) does not undergo C-terminal truncation or, at least, is not significantly C-terminally truncated. Furthermore, as the IFNG fragment containing 132 amino acid residues is active, this opens up the possibility of producing a homogenous active IFNG polypeptide in eukaryotic host cells, such as CHO cells. More particularly, the present invention relates to an IFNG polypeptide variant exhibiting IFNG activity and having the amino acid sequence shown in SEQ ID NO:12. In a highly preferred embodiment of the invention, the variant comprises at least one further modification, such as 1-10 further modifications, relative to the amino acid sequence shown in SEQ ID NO:12. A particular preferred further modification is E38N+S40T.