Dissecting the interaction network of multiprotein complexes by pairwise coexpression of subunits in E-coli

Using the human basal transcription factors TFIID and TFIIH as examples, we show that pairwise coexpression of polypeptides in Escherichia coli can be used as a tool for the identification of specifically interacting subunits within multiprotein complexes. We find that coexpression of appropriate co mbinations generally leads to an increase in the solubility and stability o f the polypeptides involved, which means that large amounts of the resultin g complexes can immediately be obtained for subsequent biochemical and stru ctural analysis. Furthermore, we demonstrate that the solubilization and/or the proper folding of a protein by its natural partner can be used as a mo nitor for deletion mapping to determine precise interaction domains. Coexpr ession can be used as an alternative or complementary approach to conventio nal techniques for interaction studies such as yeast two-hybrid analysis, G ST pulldown and immunoprecipitation. (C) 2001 Academic Press.