Whole genome phage display selects for proline-rich Boi polypeptides against Bem1p

Interaction selection by biopanning from a fragmented yeast proteome displayed on filamentous phage particles was successful in identifying proline-rich fragments of Boi1p and Boi2p. These proteins bind to the second "src homology region 3'' (SH3) domain of Bem1p, a protein of Saccharomyces cerevisiae involved in bud formation. Target Bem1p was a doubly-tagged recombinant, Bem1([Asn142-Ile551]), which strongly interacts in ELISA with a C-terminal 75 amino acids polypeptide from Cdc24p exposed on phage. The whole yeast genomic display library contained approximately 7.7 x 10(7) independent clones of sheared S. cerevisiae genomic DNA fused to a truncated M13 gene III. This study corroborates the value of fragmented-proteome display to identify strong and direct interacting protein modules.