Cloning and/or expression vectors, preparation method and their use

A gram negative bacterial vector for the cloning or expression of genes wherein said vector is obtained by a series of deletions starting from plasmid RK2 and is less than 20 kb in size and comprising:

• (a) an origin of replication, wherein said origin of replication is functional in gram negative bacteria;
• (b) the par region of plasmid RP4;
• (c) a mob locus, wherein said mob locus contains a deletion of 1.75 kb on each side of oriT;
• and (d) a multicloning site and a selectable marker.

Method for producing a protein or a metabolite, comprising

• introducing a gram negative bacterial vector, comprising:
• (a) an origin of replication, wherein said origin of replication is functional in gram negative bacteria;
• (b) the par region of plasmid RP4;
• (c) a mob locus, wherein said mob locus contains a deletion of 1.75 kb on each side of OriT;
• and (d) a recombinant DNA fragment having at least one structural gene coding for the protein sought to be made or at least one gene participating in biosynthesis of the metabolite, wherein said structural gene is under the control of genetic expression sequences into a Gram-negative bacterium;
• culturing said bacterium under conditions for expression of said gene, and recovering the protein or a metabolite produced by the bacterium.