EXPRESSION OF CDNA FRAGMENT ENCODING SPERM MEMBRANE PEPTIDE IN ESCHERICHIA-COLI

A secretory high-level expression cloning vector designated as pSBC-20 was constructed by inserting a DNA fragment encoding the signal pepti de of ompA protein into pBV 220 vector. Any foreign DNA fragment can b e inserted into the polylinker cloning sites located after the secreti on signal sequence. The cloned foreign gene is under the control of th e P-R-P-L promoter while the expression of the gene is regulated by th e cI-gene product. The products are secreted into the periplasmic spac e of bacteria or into the medium. A recombinant plasmid (pRSD-220) was constructed by inserting the 210 bp from RSD-2, a cDNA encoding a pep tide fragment of human sperm protein, into the EcoRI site of pSBC-20. The E. coli cells transformed with pRSD-220 were propagated at 30 degr ees C, then incubated at 42 degrees C for several hrs. The cloned gene product was secreted into the culture medium at a high rate. The yiel d was about 60 mg of gene product per liter of cultured medium.