Evidence for Multimerization of Neu Proteins Involved in Polysialic Acid Synthesis in Escherichia coli K1 Using Improved LexA-Based Vectors

Recently, M. Dmitrova et al. (Mol. Gen. Genet. 257:205–212, 1998) described a LexA-based genetic system to monitor protein-protein interactions in an Escherichia coli background. However, the plasmids used in this system, pMS604 and pDP804, were not readily amenable for general use. In this report, we describe modifications of both plasmids that allow fragments of DNA to be fused to either vector in any reading frame. Homodimerization and heterodimerization of full-length proteins involved in polysialic acid synthesis in E. coli K1, as well as heterodimerization between a full-length protein and a protein fragment, demonstrate the usefulness of the modified plasmids for investigating bacterial protein-protein interactions in vivo.