Diversity and censoring of landscape phage libraries

Libraries of random peptides displayed on the surface of filamentousphages are a valuable source for biospecific ligands. However,their successful use can be hindered by a disproportionate representationof different phage clones and fluctuation of their compositionthat arises during phage reproduction, which have potentialto affect efficiency of selection of clones with an optimalbinding. Therefore, there is a need to develop phage displaylibraries with extended and varied repertoires of displayedpeptides. In this work, we compared the complexity, evolutionand representation of two phage display libraries displayingforeign octamers and nonamers in 4000 copies as the N-terminalpart of the major coat protein pVIII of phage fd–tet (landscapelibraries). They were obtained by replacement of amino acids2–4 and 2–5 of pVIII with random octa- and nonamers,respectively. Statistical analysis of the libraries revealedtheir dramatic censoring and evolution during amplification.Further, a survey of both libraries for clones that bind commonselectors revealed the presence of different non-overlappingfamilies of target-specific clones in each library justifyingthe concept that different landscape libraries cover differentareas of a sequence space.