The protein–protein interaction map of Helicobacter pylori

With the availability of complete DNA sequences for many prokaryotic and eukaryotic genomes, and soon for the human genome itself, it is important to develop reliable proteome-wide approaches for a better understanding of protein function1. As elementary constituents of cellular protein complexes and pathways, protein–protein interactions are key determinants of protein function. Here we have built a large-scale protein–protein interaction map of the human gastric pathogen Helicobacter pylori. We have used a high-throughput strategy of the yeast two-hybrid assay to screen 261 H. pylori proteins against a highly complex library of genome-encoded polypeptides2. Over 1,200 interactions were identified between H. pylori proteins, connecting 46.6% of the proteome. The determination of a reliability score for every single protein–protein interaction and the identification of the actual interacting domains permitted the assignment of unannotated proteins to biological pathways.