The first ever-published protein–protein interaction map of a prokaryotic organism—the stomach ulcer-inducing bacterium Helicobacter pylori—appears in a recent issue of Nature (409, 211–215, 2000). To accomplish this task, researchers from the Institut Pasteur (Paris, France) and Hybrigenics SA (Paris, France) assigned unannotated proteins to biological pathways using yeast two-hybrids assays and high-throughput screens for selected interacting domains (SID) in a complex protein library. The SIDs were then statistically ranked based on competition for binding between fragments, and a map was generated connecting 46.6% of the 1590 H. pylori putative proteins. The researchers validated the map as a tool for revealing biological pathways and predicting protein function by searching their database with known annotated Escherichia coli orthologs and establishing similar biochemical function from the resulting H. pylori proteins. According to lead author Pierre Legrain, this new process, along with the complementary PIMRider software, should “shorten the path between genomic information and validated targets. . .leading to [drugs with] less side effects.”