[Gene cloning and expression of CTLA-4 in Streptomyces lividans]

Gene cloning and expression of CTLA-4 was performed in S. lividans with two new types of different signal peptides--vsi and gpp to investigate the secretory expression efficiency of CTLA-4. The hsCTLA-4 gene was fused to the vsi sequences and then inserted into the shuttle vector-pUWL-219. At the same time, the hsCTLA-4 was inserted into the downstream of gpp signal peptide in the plasmid pLNSP. Then the recombinant plasmids were transformed into S. lividans TK24 respectively. The two engineering strains were named as S. lividans [pUWL219-VC] and S. lividans [pLNSP/CTLA-4]. The result of SDS-PAGE and Western blotting show that the recombinant strain S. lividans [pUWL219-VC] and S. lividans [pLNSP/CTLA-4] can express CTLA-4 with about MW 13,000 which is similar to those reported earlier and have immunoactivity. It is the first time that CTLA-4 expression in S. lividans is reported.