Student Speaker: Jean-Philippe Lambert Ottawa Institute of Systems Biology, Dept of Biochemistry, Microbiology, and Immunology, University of Ottawa, Ottawa, ON, Canada Revisiting the Budding Yeast Protein Interactome: Histones, their Chaperones and Beyond Chromatin, the complex packaging of DNA with proteins, is in many ways the master control centre for the cell. Despite the critical role of chromatin most cellular functions, chromatin remains poorly studied by proteomic researchers due to significant technical hurdles. Recently we have developed a novel approach, termed modified chromatin immunopurification (or mChIP), for the purification of protein-DNA macromolecules and their subsequent analysis by mass spectrometry in Saccharomyces cerevisiae. The mChIP procedure consists of a single affinity purification step, whereby chromatin bound protein networks are isolated from mildly sonicated and gently clarified cellular extracts using magnetic beads coated with antibodies. Proof-of-principle studies based on five chromatin associated baits demonstrate that the mChIP procedure can successfully isolate protein/DNA macromolecules and further our understanding of the diverse functions of chromatin associated baits. Currently, our efforts are directed at revisiting the protein-protein interactome of several classes of chromatin associated baits such as histones, histone chaperones and lysine acetyltransferases (KAT). Selected examples of this recent effort will be provided to illustrate the novel type of information accessible through mChIP purifications.