An Escherichia coli expression vector for high-level production of heterologous proteins in fusion with CMP-KDO synthetase.

The construction of a vector which overproduces the enzyme, CTP:CMP-3-deoxy-D-manno-octulosonate cytidylyl-transferase (CMP-KDO synthetase or CKS) and its use as an expression vector for producing heterologous proteins in E. coli is described. The vector, which includes a modified lac promoter and synthetic ribosome binding site upstream of the native kdsB gene (encoding CKS), produces CKS at levels as high as 70% of the total cellular proteins. Several heterologous gene sequences have been fused to the 3'-end of the kdsB gene with resulting protein fusions produced at a level of up to 40% of the total cellular proteins.