Protein Structures Illuminate Networks

Mark B. Gerstein of Yale University and colleagues have mapped a new type of protein interaction network with information from 3-D protein structures (Science 2006, 314, 1938). Most studies of protein networks neglect the structural and chemical aspects of the interactions between proteins. But Gerstein and coworkers have annotated a map of interacting yeast proteins with structural information describing the interfaces between partners. The "hub" proteins, which interact with many different proteins, fall into two categories: those with only one or two interfaces, called "singlish interface" proteins, and those with multiple interfaces. Although the singlish-interface proteins may have many different partners, they interact with only one at a time, and such interactions are likely to be transient. In contrast, proteins with multiple interfaces can interact with several proteins simultaneously. The researchers have found that multi-interface hub proteins are twice as likely as singlish-interface ones to be necessary for survival. Furthermore, the multi-interface hub proteins evolve more slowly than singlish-interface proteins, possibly because more of the surface is involved with protein interactions.