Intracellular production of cyclic peptide libraries with SICLOPPS

Abstract

Cyclic peptides are an important class of molecules that are increasingly viewed as an ideal scaffold for inhibition of protein-protein interactions (PPI). Here we detail an approach that enables the intracellular synthesis of cyclic peptide libraries of around 108 members. The method utilizes split intein mediated circular ligation of peptides and proteins (SICLOPPS), taking advantage of split intein splicing to cyclize a library of peptide sequences. SICLOPPS allows the ring size, set residues and number of random residues within a library to be predetermined by the user. SICLOPPS libraries have been combined with a variety of cellbased screens to identify cyclic peptide inhibitors of a variety of enzymes and protein-protein interactions.