Engineering Nucleic Acid-Binding Proteins by Phage Display

In the phage display method, peptides (1 ) or protein domains (2 ,3 ) cloned as fusions to the coat proteins of filamentous bacteriophage are displayed on the capsid, which encloses the viral genome. Proteins of interest and their associated phage can be selected from a large pool of variants (a library) by affinity purification using an appropriate ligand bound to a solid support. Thus, while weakly interacting phage are removed by washing, strongly bound phage are retained and can be subsequently amplified by passage through a bacterial host. Sequential rounds of selection and amplification lead to enrichment of those clones with the highest affinity for the target ligand. The identities of these clones can then be deduced by sequencing part of the phage genome.