EXPRESSION VECTORS FOR ENHANCED PRODUCTION OF POLYPEPTIDES,PLASMIDS CONTAINING THE VECTORS, HOSTS CONTAINING THE PLASMIDS, PRODUCTS MANUFACTURED THEREBY AND RELATED METHODS

EXPRESSION VECTORS FOR ENHANCED PRODUCTION OF POLYPEPTIDES, PLASMIDS CONTAINING THE VECTORS, HOSTS CONTAINING THE PLASMIDS, PRODUCTS MANUFACTURED THEREBY AND RELATED METHODS An improved vector upon introduction into a suitable bacterial host containing the thermolabile repressor CI renders the host cell capable, upon increasing the temperature of the host cell to a temperature at which the repressor is destroyed, of effecting expression of a desired gene inserted into the vector and production of polypeptide encoded by the gene. The vector is a double-stranded DNA molecule which includes in 5' to 3' order the following: a DNA sequence which contains the promoter and operator PLOL from lambda bacteriophage; the N utilization site for binding antiterminator N protein produced by the host cell; a DNA sequence which contains a ribosomal binding site for rendering the mRNA of the desired gene capable of binding to ribosomes within the host cell; an ATG initiation codon or a DNA sequence which is converted into an ATG initiation codon upon insertion of the desired gene into the vector; a restriction enzyme site for inserting the desired gene into the vector in phase with the ATG initiation codon; and additionally a DNA sequence which contains an origin of replication from a bacterial plasmid capable of autonomous replication in the host cell and a DNA sequence which contains a gene associated with a selectable or identifiable trait which is manifested when the vector is present in the host cell.