Construction and Screening of Custom Peptide Libraries Derived from Synthetic DNA Pools.

Abstract

The latest technologic advancements in chemical synthesis of DNA and peptides led to a tremendous increase in protein engineering research. High throughput, economically feasible as well as design-flexible platforms are in much demand to construct and screen large peptide libraries for numerous applications. By combining light-directed in situ parallel oligonucleotide synthesis with biological expression systems, a novel method for the construction of large custom designed peptide libraries has been developed in this study. In this method, fully defined collections of peptides are reverse-translated into oligonucleotides for DNA synthesis, expressed in a cellular host, and then screened for the selection of peptide analogs with desired properties. Each step of this process, from design to screening, was examined and optimized to maintain initial library complexity. A variety of cellular systems, both eukaryotic and prokaryotic, were investigated for their potential as an expression host. An application to discovery of antimicrobial peptides has been demonstrated by constructing two mutant libraries coding for derivatives of Pediocin PA-1 and Plantaricin-423. Screening of these libraries resulted in identification of mutant peptides with greater activities as well as substantial knowledge on sequence-related activity that can be used to generate subsequent libraries to further optimize these peptides against selected targets. Therefore, this method presents great potential for countless applications from discovery of therapeutic peptides to gaining fundamental understanding of their biological function and characteristics.