ABSTRACT
We report an inhibitor of the homodimeric protein-protein interaction of the BCL6 oncoprotein, identified from a genetically encoded SICLOPPS library of 3.2 million cyclic hexapeptides in combination with a bacterial reverse two-hybrid system. This cyclic peptide is shown to bind the BTB domain of BCL6, disrupts its homodimerization, and subsequent binding of the SMRT2 corepressor peptide.
Subject(s)
Gene Library , Peptides, Cyclic/pharmacology , Proto-Oncogene Proteins c-bcl-6/antagonists & inhibitors , Dimerization , Molecular Structure , Peptides, Cyclic/chemistry , Peptides, Cyclic/genetics , Protein Binding , Proto-Oncogene Proteins c-bcl-6/geneticsABSTRACT
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 cell-based screens to identify cyclic peptide inhibitors of a variety of enzymes and protein-protein interactions.
Subject(s)
Inteins , Peptide Library , Peptides, Cyclic , Peptides, Cyclic/biosynthesis , Peptides, Cyclic/chemistry , Peptides, Cyclic/genetics , Peptides, Cyclic/isolation & purificationABSTRACT
The identification of initial hits is a crucial stage in the drug discovery process. Although many projects adopt high-throughput screening of small-molecule libraries at this stage, there is significant potential for screening libraries of macromolecules created using chemical biology approaches. Not only can the production of the library be directly interfaced with a cell-based assay, but these libraries also require significantly fewer resources to generate and maintain. In this context, cyclic peptides are increasingly viewed as ideal scaffolds and have proven capability against challenging targets such as protein-protein interactions. Here we discuss a range of methods used for the creation of cyclic peptide libraries and detail examples of their successful implementation.
