Reconstitution and engineering of apoptotic protein interactions on the bacterial cell surface.

The interactions between pro- and anti-apoptotic members of the Bcl-2 class of proteins control whether a cell lives or dies, and the study of these protein-protein interactions has been an area of intense research. In this report, we describe a new tool for the study and engineering of apoptotic protein interactions that is based on the flow cytometric detection of these interactions on the surface of Escherichia coli. After validation of the assay with the well-studied interaction between the Bak(72-87) peptide and the anti-apoptotic protein Bcl-x(L), the effect of both increasing and decreasing Bak peptide length on Bcl-x(L) binding was investigated.