Affinity Selection of DNA-Binding Proteins from Yeast Genomic DNA Libraries by Improved X Phage Display Vector1

Phage display is a useful means of identifying and selecting proteins of interest that bind specific targets. In order to examine the potential of phage display for the genome-wide screening of DNA-binding proteins, we constructed yeast genomic libraries using Xfoo-based vectors devised in this work. After affinity selection using GAL4 UASG as a probe, phages expressing GAL4 were enriched approximately 5 x lO'-fold from the li-brary. Approximately 90 % of polypeptides encoded in correct translation reading frames by the selected phages were known or putative polynucleotide-binding proteins. This re-sult clearly indicates that the modified lambda phage display vector in combination with our enrichment technique has great potential for the enrichment of DNA-binding proteins in a sequence-specific manner. Key words: colicin E3, DNA-binding protein, GAL4, phage display, sequence-specific selection. The genome sequencing projects have resulted in the accu-mulation of a wealth of protein sequences, many of which remain to be analyzed. The identification of interactin