A small-molecule approach to the proteomic study of interaction domains

ORGN 693

David J. Austin, Elizabeth J. Videlock, Victor K. Chung, Michael A. Mohan, and Timothy M. Strok. Department of Chemistry, Yale University, 225 Prospect Street, New Haven, CT 06520
We have recently been developing a functional protein resource for the small-molecule investigation of phosphopeptide binding interaction domains involved in protein-protein interactions. Interaction domains, as modular segments of larger proteins, have the ability to fold and function independently and are involved in a variety of signal transduction and cell regulatory mechanisms. In addition, many of these domains are known to interact with peptides and non-peptidic small molecules. Our approach is to use small-molecule probes, in conjunction with cDNA phage display, to both identify and evaluate interaction domains in the human proteome. We recently synthesized a degenerate phosphotyrosine peptide probe pYZZZ (where Z=all amino acids except tryptophan and cysteine), based on the canonical SH2-domain binding peptide motif. Screening of cDNA phage display libraries lead to the isolation of a number of SH2-domain displaying phage particles. Subsequent on-phage binding analyisis showed both dose-dependent phosphopeptide binding and phosphate-dependent binding, which is consistent with the SH2 domain phenotype. Future goals involve the isolation of additional SH2 domains from the human proteome in order to construct SH2-domain phage arrays, in a multi-well plate format, which will allow the rapid evaluation of SH2-domain binding selectivity for any phosphoprotein or probe.