Redefinition of the yeast two-hybrid system in dialogue with changing priorities in biological research

Examination of the pattern of reagent creation and application in the two-h ybrid system since 1989 reveals the expansion of a simple core technology t o address increasingly sophisticated problems in protein interaction. As th e technology has matured, its clear suitability for targe-scale proteomic p rojects has made a major focus of its application the generation of global organismal protein interaction networks. In an inversion of emphasis, the i ncreasing availability of such information now provides a master plan with the potential to specify the most promising directions for biological inves tigations (i.e., by directing the physiological validation of predicted cri tical protein-protein interactions). Recent derivatives of the two-hybrid s ystem enable rite targeting of such key interactions by facilitating the id entification of essential amino acids conferring protein interaction specif icity and of small molecules that selectively disrupt defined interaction p airs. Finally, the creation of mammalian expression systems based oil two-h ybrid principles became a new toot to create and probe novel biological sys tems. Taken in sum, this trajectory emphasizes the point that the creation of tools and the evolution of the idea of what is an interesting biological problem are in intimate dialogue.